JPWO2016140081A1 - Lithographic lower layer film forming material, Lithographic lower layer film forming composition, Lithographic lower layer film, resist pattern forming method, and circuit pattern forming method - Google Patents

Abstract

The present invention provides a material for forming a lower layer film for lithography, comprising a cyanate ester compound, obtained by cyanating a modified naphthalene formaldehyde resin.

Description

  The present invention relates to a material for forming an underlayer film for lithography, a composition for forming an underlayer film for lithography, an underlayer film for lithography, a method for forming a resist pattern, and a method for forming a circuit pattern.

  In the manufacture of semiconductor devices, microfabrication by lithography using a photoresist material is performed, but in recent years, further miniaturization by a pattern rule has been demanded as LSI is highly integrated and increased in speed. In lithography using light exposure, which is currently used as a general-purpose technology, the limit of the essential resolution derived from the wavelength of the light source is approaching.

  The light source for lithography used in forming the resist pattern is shortened from KrF excimer laser (248 nm) to ArF excimer laser (193 nm). However, as the miniaturization of the resist pattern progresses, there arises a problem of resolution or a problem that the resist pattern collapses after development. Therefore, it is desired to reduce the thickness of the resist. However, simply thinning the resist makes it difficult to obtain a resist pattern film thickness sufficient for substrate processing. Therefore, not only a resist pattern but also a process in which a resist underlayer film is formed between the resist and a semiconductor substrate to be processed and the resist underlayer film also has a function as a mask during substrate processing has become necessary.

  Currently, various resist underlayer films for such processes are known. For example, unlike a conventional resist underlayer film having a high etching rate, a terminal layer is removed by applying a predetermined energy as a resist underlayer film for lithography having a dry etching rate selection ratio close to that of a resist. A material for forming a lower layer film for a multilayer resist process has been proposed which contains at least a resin component having a substituent that generates a sulfonic acid residue and a solvent (see, for example, Patent Document 1). Also, resist underlayer film materials containing a polymer having a specific repeating unit have been proposed as a material for realizing a resist underlayer film for lithography having a lower dry etching rate selectivity than resist (for example, Patent Documents). 2). Furthermore, in order to realize a resist underlayer film for lithography having a low dry etching rate selection ratio compared with a semiconductor substrate, a repeating unit of acenaphthylenes and a repeating unit having a substituted or unsubstituted hydroxy group are copolymerized. A resist underlayer film material containing a polymer is proposed (see, for example, Patent Document 3).

  On the other hand, as a material having high etching resistance in this type of resist underlayer film, an amorphous carbon underlayer film formed by CVD using methane gas, ethane gas, acetylene gas or the like as a raw material is well known.

  Also proposed is a composition for forming a lower layer film for lithography containing a naphthalene formaldehyde polymer containing a specific structural unit and an organic solvent as a material that is excellent in optical properties and etching resistance and is soluble in a solvent and applicable to a wet process. (See, for example, Patent Documents 4 and 5).

  Regarding the formation method of the intermediate layer used in the formation of the resist underlayer film in the three-layer process, for example, a silicon nitride film formation method (see, for example, Patent Document 6) or a silicon nitride film CVD formation method (for example, Patent Document 7) is known. As an intermediate layer material for a three-layer process, a material containing a silsesquioxane-based silicon compound is known (for example, see Patent Documents 8 and 9).

JP 2004-177668 A JP 2004-271838 A JP-A-2005-250434 International Publication No. 2009/072465 International Publication No. 2011/034062 JP 2002-334869 A International Publication No. 2004/066377 JP 2007-226170 A JP 2007-226204 A

  As described above, a number of materials for forming a lower layer film for lithography have been proposed in the past, but not only have high solvent solubility to which wet processes such as spin coating and screen printing can be applied, but also heat resistance and etching. There is nothing that combines resistance at a high level, and the development of new materials is required.

  Accordingly, the present invention has been made in view of the above-described problems of the prior art, and can be applied to a wet process, and is useful for forming a photoresist underlayer film excellent in heat resistance and etching resistance. An object is to provide a forming material.

  As a result of intensive studies to solve the above-described problems of the prior art, the present inventors have achieved heat resistance by using a material for forming an underlayer film containing a cyanate ester compound obtained by cyanating a modified naphthalene formaldehyde resin. The inventors have found that a photoresist underlayer film having excellent properties and etching resistance can be obtained, and have completed the present invention. That is, the present invention is as follows.

（式（１）中、Ａｒ_１は、各々独立に芳香環構造を示し、Ｒ_１は、各々独立にメチレン基、メチレンオキシ基、メチレンオキシメチレン基、若しくはオキシメチレン基、又はこれらの連結しているものを示し、Ｒ_２は、各々独立に一価の置換基である水素原子、アルキル基又はアリール基を示し、Ｒ_３は、各々独立に炭素数が１〜３であるアルキル基、アリール基、ヒドロキシ基、又はヒドロキシメチレン基を示し、ｍは、１以上の整数を示し、ｎは、０以上の整数を示し、各繰り返し単位の配列は任意である。ｋは、シアナト基の結合個数である１〜３の整数を示し、ｘは、Ｒ_２の結合個数である「Ａｒ_１の結合可能な個数−（ｋ＋２）」の整数を示し、ｙは、０〜４の整数を示す。）
［３］
前記変性ナフタレンホルムアルデヒド樹脂は、ナフタレンホルムアルデヒド樹脂、又は脱アセタール結合ナフタレンホルムアルデヒド樹脂を、ヒドロキシ置換芳香族化合物を用いて変性させて得られる樹脂である、［１］又は［２］に記載のリソグラフィー用下層膜形成用材料。
［４］
前記ヒドロキシ置換芳香族化合物は、フェノール、２，６−キシレノール、ナフトール、ジヒドロキシナフタレン、ビフェノール、ヒドロキシアントラセン、及びジヒドロキシアントラセンからなる群より選択される１種又は２種以上である、［３］に記載のリソグラフィー用下層膜形成用材料。
［５］
前記シアン酸エステル化合物の重量平均分子量が、２００以上２５０００以下である、［１］〜［４］のいずれかに記載のリソグラフィー用下層膜形成用材料。
［６］
前記式（１）で表される化合物は、下記式（１−１）で表される化合物である、［２］〜［５］のいずれかに記載のリソグラフィー用下層膜形成用材料。

（式（１−１）中、Ｒ_１〜Ｒ_３、ｋ、ｍ、ｎ及びｙは、前記式（１）で説明したものと同義であり、ｘは、（６−ｋ）の整数を示す。）
［７］
前記式（１−１）で表される化合物は、下記式（１−２）で表される化合物である、［６］に記載のリソグラフィー用下層膜形成用材料。

（式（１−２）中、Ｒ_１、ｍ、ｎは、前記式（１）で説明したものと同義である。）
［８］
［１］〜［７］のいずれかに記載のリソグラフィー用下層膜形成用材料と、溶媒と、を含有する、リソグラフィー用下層膜形成用組成物。
［９］
酸発生剤を、さらに含有する、［８］に記載のリソグラフィー用下層膜形成用組成物。
［１０］
架橋剤を、さらに含有する、［８］又は［９］に記載のリソグラフィー用下層膜形成用組成物。
［１１］
［８］〜［１０］のいずれかに記載のリソグラフィー用下層膜形成用組成物を用いて形成される、リソグラフィー用下層膜。
［１２］
基板上に、［８］〜［１０］のいずれかに記載の下層膜形成用組成物を用いて、下層膜を形成する工程と、
前記下層膜上に、少なくとも１層のフォトレジスト層を形成する工程と、
前記フォトレジスト層の所定の領域に放射線を照射し、現像する工程と、を有する、
レジストパターン形成方法。
［１３］
基板上に、［８］〜［１０］のいずれかに記載の下層膜形成用組成物を用いて、下層膜を形成する工程と、
前記下層膜上に、珪素原子を含有するレジスト中間層膜材料を用いて、中間層膜を形成する工程と、
前記中間層膜上に、少なくとも１層のフォトレジスト層を形成する工程と、
前記フォトレジスト層の所定の領域に放射線を照射し、現像したレジストパターンを形成する工程と、
前記レジストパターンをマスクとして、前記中間層膜をエッチングし、中間層膜パターンを形成する工程と、
前記中間層膜パターンをエッチングマスクとして、前記下層膜をエッチングし、下層膜パターンを形成する工程と、
前記下層膜パターンをエッチングマスクとして、前記基板をエッチングし、基板パターンを形成する工程と、を有する、
回路パターン形成方法。[1]
A material for forming an underlayer film for lithography, comprising a cyanate ester compound obtained by cyanating a modified naphthalene formaldehyde resin.
[2]
The material for forming a lower layer film for lithography according to [1], wherein the cyanate ester compound is a compound represented by the following formula (1).

(In formula (1), each Ar ₁ independently represents an aromatic ring structure, and each R ₁ independently represents a methylene group, a methyleneoxy group, a methyleneoxymethylene group, or an oxymethylene group, or a combination thereof. R ₂ represents each independently a monovalent substituent hydrogen atom, alkyl group or aryl group, and R ₃ each independently represents an alkyl group or aryl group having 1 to 3 carbon atoms. , Hydroxy group, or hydroxymethylene group, m represents an integer of 1 or more, n represents an integer of 0 or more, and the arrangement of each repeating unit is arbitrary, k is the number of bonds of the cyanate group. An integer of 1 to 3 is shown, x is an integer of “the number of bonds of Ar ₁ − (k + 2)” which is the number of bonds of R ₂ , and y is an integer of 0 to 4.
[3]
The lower layer for lithography according to [1] or [2], wherein the modified naphthalene formaldehyde resin is a resin obtained by modifying a naphthalene formaldehyde resin or a deacetal-bonded naphthalene formaldehyde resin with a hydroxy-substituted aromatic compound. Film forming material.
[4]
[3] The hydroxy-substituted aromatic compound is one or more selected from the group consisting of phenol, 2,6-xylenol, naphthol, dihydroxynaphthalene, biphenol, hydroxyanthracene, and dihydroxyanthracene. Material for forming a lower layer film for lithography.
[5]
The material for forming a lower layer film for lithography according to any one of [1] to [4], wherein the cyanate ester compound has a weight average molecular weight of 200 to 25,000.
[6]
The compound represented by the formula (1) is a material for forming an underlayer film for lithography according to any one of [2] to [5], which is a compound represented by the following formula (1-1).

(In Formula (1-1), R _{1 to} R ₃ , k, m, n, and y are as defined in Formula (1) above, and x represents an integer of (6-k). .)
[7]
The compound represented by the formula (1-1) is a material for forming an underlayer film for lithography according to [6], which is a compound represented by the following formula (1-2).

(In formula (1-2), R ₁ , m and n have the same meanings as described in formula (1).)
[8]
A composition for forming an underlayer film for lithography, comprising the material for forming an underlayer film for lithography according to any one of [1] to [7] and a solvent.
[9]
The composition for forming a lower layer film for lithography according to [8], further comprising an acid generator.
[10]
The composition for forming a lower layer film for lithography according to [8] or [9], further comprising a crosslinking agent.
[11]
A lower layer film for lithography formed using the composition for forming a lower layer film for lithography according to any one of [8] to [10].
[12]
Forming a lower layer film on the substrate using the lower layer film forming composition according to any one of [8] to [10];
Forming at least one photoresist layer on the lower layer film;
Irradiating a predetermined region of the photoresist layer with radiation and developing,
Resist pattern forming method.
[13]
Forming a lower layer film on the substrate using the lower layer film forming composition according to any one of [8] to [10];
On the lower layer film, a step of forming an intermediate layer film using a resist intermediate layer film material containing silicon atoms,
Forming at least one photoresist layer on the intermediate layer film;
Irradiating a predetermined region of the photoresist layer with radiation to form a developed resist pattern;
Etching the intermediate layer film using the resist pattern as a mask to form an intermediate layer film pattern;
Etching the lower layer film using the intermediate layer film pattern as an etching mask to form a lower layer film pattern;
Using the lower layer film pattern as an etching mask, etching the substrate to form a substrate pattern,
Circuit pattern forming method.

  The material for forming an underlayer film for lithography according to the present invention can be applied to a wet process and is useful for forming a photoresist underlayer film having excellent heat resistance and etching resistance.

  Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described. The following embodiment is an exemplification for explaining the present invention, and the present invention is not limited only to the embodiment.

[Material for forming lower layer film for lithography]
The material for forming a lower layer film for lithography of the present embodiment (hereinafter also simply referred to as “lower layer film forming material”) includes a cyanate ester compound obtained by cyanating a modified naphthalene formaldehyde resin. The material for forming a lower layer film for lithography of this embodiment can be applied to a wet process. In addition, the material for forming a lower layer film for lithography of this embodiment has an aromatic structure and also has a cyanate group, and the cyanate group causes a crosslinking reaction by high-temperature baking even alone, and has high heat resistance. Expresses sex. As a result, deterioration of the film during high-temperature baking is suppressed, and a lower layer film having excellent etching resistance against oxygen plasma etching or the like can be formed. Furthermore, although the material for forming a lower layer film for lithography of this embodiment has an aromatic structure, it has high solubility in an organic solvent, high solubility in a safe solvent, and embedding characteristics in a stepped substrate. In addition, the flatness of the film is excellent, and the stability of the product quality is good. In addition, since the material for forming a lower layer film for lithography of the present embodiment is also excellent in adhesion with a resist layer or a resist intermediate layer film material, an excellent resist pattern can be obtained.

[Modified naphthalene formaldehyde resin]
The modified naphthalene formaldehyde resin of this embodiment is obtained by modifying a naphthalene formaldehyde resin or a deacetal-bonded naphthalene formaldehyde resin with, for example, a hydroxy-substituted aromatic compound represented by the following formula (2).

式（２）中、Ａｒ_１は、芳香環構造を示す。Ｒ_２は、各々独立に一価の置換基である水素原子、アルキル基、又はアリール基を示す。上記芳香環の置換基は、任意の位置を選択できる。ａは、ヒドロキシ基の結合個数である１〜３の整数を示す。ｂは、Ｒの結合個数である、Ａｒ_１がベンゼン構造を示すときは（５−ａ）、ナフタレン構造を示すときは（７−ａ）、ビフェニレン構造を示すときは（９−ａ）を示す。

In formula (2), Ar ₁ represents an aromatic ring structure. R ₂ each independently represents a monovalent substituent hydrogen atom, alkyl group, or aryl group. Arbitrary positions can be selected for the substituent of the aromatic ring. a represents an integer of 1 to 3, which is the number of bonded hydroxy groups. b represents the number of bonds of R. When Ar ₁ represents a benzene structure, (5-a), when naphthalene structure is represented (7-a), when biphenylene structure is represented, (9-a) is represented. .

  Here, the naphthalene formaldehyde resin is obtained by condensation reaction of a naphthalene compound and formaldehyde in the presence of an acidic catalyst, and the deacetal-bonded naphthalene formaldehyde resin is a naphthalene formaldehyde resin in the presence of water and an acidic catalyst. It is obtained by processing with.

  Hereinafter, the naphthalene formaldehyde resin, the deacetal-bonded naphthalene formaldehyde resin, and the modified naphthalene formaldehyde will be described.

[Naphthalene formaldehyde resin and its production method]
Naphthalene formaldehyde resin is a resin obtained by subjecting a naphthalene compound and formaldehyde to a condensation reaction in the presence of an acidic catalyst.

  The naphthalene compound used for the condensation reaction is naphthalene and / or naphthalenemethanol. Naphthalene and naphthalenemethanol are not particularly limited, and industrially available ones can be used.

  The formaldehyde used for the condensation reaction is not particularly limited, and examples thereof include an industrially available aqueous formaldehyde solution. In addition, compounds that generate formaldehyde such as paraformaldehyde and trioxane can also be used. From the viewpoint of suppressing gelation, an aqueous formaldehyde solution is preferable.

  The molar ratio of the naphthalene compound to formaldehyde in the condensation reaction is preferably 1: 1 to 1:20, more preferably 1: 1.5 to 1: 17.5, and even more preferably 1: 2 to 1:15. , More preferably 1: 2 to 1: 12.5, even more preferably 1: 2 to 1:10. By setting it as such a range, it exists in the tendency which can maintain the yield of the naphthalene formaldehyde resin obtained comparatively high, and can reduce the quantity of formaldehyde which remains unreacted.

  As the acidic catalyst used in the condensation reaction, known inorganic acids and organic acids can be used. For example, inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, hydrobromic acid, hydrofluoric acid, oxalic acid, malon Acid, succinic acid, adipic acid, sebacic acid, citric acid, fumaric acid, maleic acid, formic acid, p-toluenesulfonic acid, methanesulfonic acid, trifluoroacetic acid, dichloroacetic acid, trichloroacetic acid, trifluoromethanesulfonic acid, benzenesulfonic acid , Organic acids such as naphthalene sulfonic acid and naphthalene disulfonic acid, Lewis acids such as zinc chloride, aluminum chloride, iron chloride and boron trifluoride, solids such as silicotungstic acid, phosphotungstic acid, silicomolybdic acid or phosphomolybdic acid Examples include acids. Among these, from the viewpoint of production, sulfuric acid, oxalic acid, citric acid, p-toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, naphthalenesulfonic acid, naphthalenedisulfonic acid, and phosphotungstic acid are included. preferable.

  The amount of the acidic catalyst used is preferably 0.0001 parts by mass to 100 parts by mass, more preferably 0.001 parts by mass to 85 parts by mass with respect to the total amount (100 parts by mass) of the naphthalene compound and formaldehyde. More preferably, it is 0.001 parts by mass or more and 70 parts by mass or less. By setting it as such a range, it exists in the tendency for a suitable reaction rate to be obtained and to prevent the increase in the resin viscosity based on a large reaction rate. Further, the acidic catalyst may be charged all at once or charged in parts.

  The above condensation reaction is preferably carried out in the presence of an acidic catalyst and under normal pressure, and is carried out at a temperature not lower than the temperature at which the raw materials to be used are compatible (more preferably 80 to 300 ° C.) or while distilling off the generated water. . The reaction pressure may be normal pressure or increased pressure. If necessary, an inert gas such as nitrogen, helium, or argon may be passed through the system.

  Further, if necessary, a solvent inert to the condensation reaction can also be used. Examples of the solvent include aromatic hydrocarbon solvents such as toluene, ethylbenzene, and xylene; saturated aliphatic hydrocarbon solvents such as heptane and hexane; alicyclic hydrocarbon solvents such as cyclohexane; dioxane, dibutyl ether, and the like. Ether solvents of the above; ketone solvents such as methyl isobutyl ketone; carboxylic acid ester solvents such as ethyl propionate; and carboxylic acid solvents such as acetic acid.

  The above condensation reaction is not particularly limited, but when alcohol coexists, the end of the resin is sealed with alcohol to obtain a low molecular weight, low dispersion (narrow molecular weight distribution) naphthalene formaldehyde resin, and solvent solubility even after modification From the viewpoint of providing a resin having a good and low melt viscosity, it is preferably carried out in the presence of alcohol. The said alcohol is not specifically limited, For example, C1-C12 monool and C1-C12 diol are mentioned. The above alcohols may be added alone or in combination. Of these, propanol, butanol, octanol, and 2-ethylhexanol are preferable from the viewpoint of productivity of naphthalene formaldehyde resin. When alcohol coexists, the usage-amount of alcohol is not specifically limited, For example, 1-10 equivalent of hydroxyl groups in alcohol are preferable with respect to 1 equivalent of methylol groups in naphthalene methanol.

  The condensation reaction may be a simultaneous addition of a naphthalene compound, formaldehyde, and an acidic catalyst to the reaction system, or a condensation reaction in which a naphthalene compound is sequentially added to a system in which formaldehyde and an acidic catalyst are present. The above sequential addition method is preferable from the viewpoint of increasing the oxygen concentration in the obtained resin and allowing it to react more with the hydroxy-substituted aromatic compound in the subsequent modification step.

  The reaction time in the condensation reaction is preferably 0.5 to 30 hours, more preferably 0.5 to 20 hours, and further preferably 0.5 to 10 hours. By setting it as such a range, it exists in the tendency for resin which has the target property to be obtained economically and industrially advantageously.

  The reaction temperature in the condensation reaction is preferably 80 to 300 ° C, more preferably 85 to 270 ° C, and still more preferably 90 to 240 ° C. By setting it as such a range, it exists in the tendency for resin which has the target property to be obtained economically and industrially advantageously.

  After completion of the reaction, if necessary, the solvent is further added and diluted, and then allowed to stand to separate into two phases, and after separating the resin phase that is an oil phase and the aqueous phase, the mixture is further washed with water. The naphthalene formaldehyde resin can be obtained by completely removing the catalyst and removing the added solvent and unreacted raw material by a general method such as distillation.

  In the naphthalene formaldehyde resin obtained by the above reaction, at least a part of the naphthalene ring is crosslinked with a bond represented by the following formula (3) and / or the following formula (4).

式（３）中、ｃは、１〜１０の整数を示す。

In formula (3), c represents an integer of 1 to 10.

式（４）中、ｄは、０〜１０の整数を示す。

In formula (4), d shows the integer of 0-10.

  Further, at least a part of the naphthalene ring is a bond in which a bond represented by the above formula (3) and a bond represented by the following formula (5) are randomly arranged, for example, the following formulas (6), (7 ) And (8) may be cross-linked.

式（５）中、ｄは、０〜１０の整数を示す。

In formula (5), d shows the integer of 0-10.

[Deacetal-bonded naphthalene formaldehyde resin and method for producing the same]
The deacetal-bound naphthalene formaldehyde resin is obtained by treating the naphthalene formaldehyde resin in the presence of water and an acidic catalyst. In the present embodiment, the treatment is referred to as deacetalization.

  Deacetal-bonded naphthalene formaldehyde resin is deacetalized to reduce the bond between oxymethylene groups not via a naphthalene ring, and c in formula (3) and / or d in formula (4) are small. It points to what became. The deacetal-bonded naphthalene formaldehyde resin thus obtained has a larger amount of residue at the time of thermal decomposition of the resin obtained after modification, that is, the mass reduction rate is lower than that of the naphthalene formaldehyde resin.

  The naphthalene formaldehyde resin can be used for the deacetalization.

  The acidic catalyst used for the deacetalization can be appropriately selected from known inorganic acids and organic acids. For example, inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, hydrobromic acid, hydrofluoric acid, and oxalic acid , Malonic acid, succinic acid, adipic acid, sebacic acid, citric acid, fumaric acid, maleic acid, formic acid, p-toluenesulfonic acid, methanesulfonic acid, trifluoroacetic acid, dichloroacetic acid, trichloroacetic acid, trifluoromethanesulfonic acid, benzene Organic acids such as sulfonic acid, naphthalenesulfonic acid, naphthalene disulfonic acid, Lewis acids such as zinc chloride, aluminum chloride, iron chloride, boron trifluoride, silicotungstic acid, phosphotungstic acid, silicomolybdic acid or phosphomolybdic acid Solid acids such as Among these, from the viewpoint of production, sulfuric acid, oxalic acid, citric acid, p-toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, naphthalenesulfonic acid, naphthalenedisulfonic acid, and phosphotungstic acid are included. preferable.

  The deacetalization is preferably carried out in the presence of an acidic catalyst and under normal pressure, and at a temperature equal to or higher than the temperature at which the raw materials used are compatible (more preferably, 80 to 300 ° C.), the water used is dropped into the system or water vapor. While spraying as. The water in the system may be distilled off or refluxed. However, it is preferable that the water is distilled off together with low-boiling components such as formaldehyde generated in the reaction because the acetal bond can be efficiently removed. The reaction pressure may be normal pressure or increased pressure. If necessary, an inert gas such as nitrogen, helium, or argon may be passed through the system.

  If necessary, a solvent inert to deacetalization can also be used. Examples of the solvent include aromatic hydrocarbon solvents such as toluene, ethylbenzene and xylene, saturated aliphatic hydrocarbon solvents such as heptane and hexane, alicyclic hydrocarbon solvents such as cyclohexane, dioxane, dibutyl ether and the like. Ether solvents, ketone solvents such as methyl isobutyl ketone, carboxylic acid ester solvents such as ethyl propionate, and carboxylic acid solvents such as acetic acid.

  The amount of the acidic catalyst used is preferably 0.0001 parts by mass or more and 100 parts by mass or less, more preferably 0.001 parts by mass or more and 85 parts by mass or less, still more preferably 0.001 parts by mass or less, with respect to 100 parts by mass of the naphthalene formaldehyde resin. It is 001 mass parts or more and 70 mass parts or less. By setting it as such a range, it exists in the tendency for a suitable reaction rate to be obtained and to prevent the increase in the resin viscosity based on a large reaction rate. Further, the acidic catalyst may be charged all at once or charged in parts.

  Although the water used for the said deacetalization will not be specifically limited if it can be used industrially, For example, a tap water, distilled water, ion-exchange water, a pure water, and an ultrapure water is mentioned.

  The amount of water used is preferably 0.1 parts by mass or more and 10,000 parts by mass or less, more preferably 1.0 part by mass or more and 5000 parts by mass or less, and more preferably 10 parts by mass or more and 3000 parts by mass with respect to 100 parts by mass of the naphthalene formaldehyde resin. Part or less is more preferable.

  The reaction time in the deacetalization is preferably 0.5 to 20 hours, more preferably 1 to 15 hours, and further preferably 2 to 10 hours. By setting it as such a range, it exists in the tendency for resin which has the target property to be obtained economically and industrially.

  In the deacetalization, the reaction temperature is preferably 80 to 300 ° C, more preferably 85 to 270 ° C, and further preferably 90 to 240 ° C. By setting it as such a range, it exists in the tendency for resin which has the target property to be obtained economically and industrially.

  The deacetal-bonded naphthalene formaldehyde resin has a lower oxygen concentration and a higher softening point than naphthalene formaldehyde resin. For example, when the above-mentioned acidic catalyst is used in an amount of 0.05 parts by mass, the amount of water used is 2000 parts by mass, the reaction time is 5 hours, and the reaction temperature is 150 ° C., the oxygen concentration is about 0.1 to 8.0% by mass. It becomes low and the softening point tends to increase by about 3 to 100 ° C.

[Modified naphthalene formaldehyde resin and method for producing the same]
The modified naphthalene formaldehyde resin is a modified condensation reaction by heating the naphthalene formaldehyde resin or the deacetal-bonded naphthalene formaldehyde resin and, for example, a hydroxy-substituted aromatic compound represented by the following formula (2) in the presence of an acidic catalyst. Can be obtained. In the present embodiment, the “modified condensation reaction” is referred to as modification.

上記式（２）中、Ａｒ_１は、芳香環構造を示す。Ｒ_２は、各々独立に一価の置換基である水素原子、アルキル基、又はアリール基を示す。上記芳香環の置換基は、任意の位置を選択できる。ａは、ヒドロキシ基の結合個数である１〜３の整数を示す。ｂは、Ｒの結合個数である、Ａｒ_１がベンゼン構造を示すときは（５−ａ）、ナフタレン構造を示すときは（７−ａ）、ビフェニレン構造を示すときは（９−ａ）を示す。

In the above formula (2), Ar ₁ represents an aromatic ring structure. R ₂ each independently represents a monovalent substituent hydrogen atom, alkyl group, or aryl group. Arbitrary positions can be selected for the substituent of the aromatic ring. a represents an integer of 1 to 3, which is the number of bonded hydroxy groups. b represents the number of bonds of R. When Ar ₁ represents a benzene structure, (5-a), when naphthalene structure is represented (7-a), when biphenylene structure is represented, (9-a) is represented. .

In the above formula (2), examples of the aromatic ring include, but are not particularly limited to, a benzene ring, a naphthalene ring, and an anthracene ring. The alkyl group for R ₂ is preferably a linear or branched alkyl group having 1 to 8 carbon atoms, more preferably a linear or branched alkyl group having 1 to 4 carbon atoms. Specific examples include, but are not limited to, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a sec-butyl group, and a tert-butyl group. Furthermore, examples of the aryl group for R ₂ include, but are not limited to, a phenyl group, a p-tolyl group, a naphthyl group, and an anthryl group.

  The hydroxy-substituted aromatic compound represented by the formula (2) is one or more selected from the group consisting of phenol, 2,6-xylenol, naphthol, dihydroxynaphthalene, biphenol, hydroxyanthracene, and dihydroxyanthracene. It is preferable that

  The amount of the hydroxy-substituted aromatic compound used is preferably 0.1 mol or more and 5.0 mol or less with respect to 1 mol of oxygen mole contained in the naphthalene formaldehyde resin or deacetal-bonded naphthalene formaldehyde resin, and 0.2 mol More preferably, it is 4.0 mol or less, and more preferably 0.3 mol or more and 3.0 mol or less. By setting it as such a range, it exists in the tendency which can maintain the yield of the modified | denatured naphthalene resin obtained comparatively high, and can reduce the quantity of the hydroxy substituted aromatic compound which remains unreacted.

The molecular weight of the resulting resin is affected by the number of moles of oxygen contained in the naphthalene formaldehyde resin or deacetal-bound naphthalene formaldehyde resin and the amount of hydroxy-substituted aromatic compound used, and the molecular weight decreases as both increase. Here, the number of moles of oxygen contained can be calculated according to the following calculation formula by measuring the oxygen concentration (mass%) in the naphthalene formaldehyde resin or the deacetal-bound naphthalene formaldehyde resin by organic elemental analysis.
Number of moles of oxygen contained (mol) = Amount of resin used (g) × oxygen concentration (mass%) / 16

  The acidic catalyst used in the modification reaction can be appropriately selected from known inorganic acids and organic acids. For example, inorganic acids such as hydrochloric acid, sulfuric acid, phosphoric acid, hydrobromic acid, hydrofluoric acid, oxalic acid, Malonic acid, succinic acid, adipic acid, sebacic acid, citric acid, fumaric acid, maleic acid, formic acid, p-toluenesulfonic acid, methanesulfonic acid, trifluoroacetic acid, dichloroacetic acid, trichloroacetic acid, trifluoromethanesulfonic acid, benzenesulfone Acids, organic acids such as naphthalene sulfonic acid, naphthalene disulfonic acid, Lewis acids such as zinc chloride, aluminum chloride, iron chloride, boron trifluoride, silicotungstic acid, phosphotungstic acid, silicomolybdic acid or phosphomolybdic acid Solid acid. Among these, from the viewpoint of production, sulfuric acid, oxalic acid, citric acid, p-toluenesulfonic acid, methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, naphthalenesulfonic acid, naphthalenedisulfonic acid, and phosphotungstic acid are included. preferable.

  The amount of the acidic catalyst used is preferably 0.0001 parts by mass or more and 100 parts by mass or less, more preferably 0.001 parts by mass or more and 85 parts by mass with respect to 100 parts by mass of the naphthalene formaldehyde resin or deacetal-bonded naphthalene formaldehyde resin. It is not more than part by mass, more preferably not less than 0.001 part by mass and not more than 70 parts by mass. By setting it as such a range, it exists in the tendency for a suitable reaction rate to be obtained and to suppress the increase in the resin viscosity based on the large reaction rate. Further, the acidic catalyst may be charged all at once or charged in a divided manner.

  The above modification reaction is preferably performed in the presence of an acidic catalyst under normal pressure, and heated to reflux at a temperature equal to or higher than the temperature at which the raw materials to be used are compatible (more preferably 80 to 300 ° C.) or while distilling off generated water. Do. The reaction pressure may be normal pressure or increased pressure. If necessary, an inert gas such as nitrogen, helium, or argon may be passed through the system.

  If necessary, a solvent inert to the modification reaction can also be used. Examples of the solvent include aromatic hydrocarbon solvents such as toluene, ethylbenzene, and xylene; saturated aliphatic hydrocarbon solvents such as heptane and hexane; alicyclic hydrocarbon solvents such as cyclohexane; dioxane, dibutyl ether, and the like. Ether solvents such as 2-propanol, ketone solvents such as methyl isobutyl ketone, carboxylic acid ester solvents such as ethyl propionate, and carboxylic acid solvents such as acetic acid.

  The reaction time in the modification reaction is preferably 0.5 to 20 hours, more preferably 1 to 15 hours, and further preferably 2 to 10 hours. By setting it as such a range, it exists in the tendency for resin which has the target property to be obtained economically and industrially advantageously.

  In the modification reaction, the reaction temperature is preferably 80 to 300 ° C, more preferably 85 to 270 ° C, and further preferably 90 to 240 ° C. By setting it as such a range, it exists in the tendency for resin which has the target property to be obtained economically and industrially advantageously.

  After completion of the reaction, if necessary, the solvent is further added and diluted, and then allowed to stand to separate into two phases, and after separating the resin phase that is an oil phase and the aqueous phase, the mixture is further washed with water. A modified naphthalene formaldehyde resin is obtained by completely removing the catalyst and removing the added solvent and unreacted raw material by a general method such as distillation.

  The modified naphthalene formaldehyde resin has a larger amount of residue at the time of thermal decomposition (a decrease in mass reduction rate) and a higher hydroxyl value than naphthalene formaldehyde resin or deacetal-bound formaldehyde resin. For example, when the amount of the acidic catalyst described above is 0.05 parts by mass, the reaction time is 5 hours, and the reaction temperature is 200 ° C., the amount of residue at the time of thermal decomposition increases by about 1 to 50%, and the hydroxyl group The value tends to increase by about 1 to 300.

  Although the modified naphthalene formaldehyde resin obtained by the said manufacturing method is not specifically limited, It can represent with following formula (9).

式（９）中、Ａｒ_１は、芳香環構造を示し、Ｒ_１は、各々独立にメチレン基、メチレンオキシ基、メチレンオキシメチレン基、若しくはオキシメチレン基、又はこれらが連結していているものを示す。Ｒ_２は、各々独立に一価の置換基である水素原子、アルキル基、又はアリール基を示し、Ｒ_３は、各々独立に炭素数が１〜３のアルキル基、アリール基、ヒドロキシ基、又はヒドロキシメチレン基を示す。ｍは、１以上の整数を示し、ｎは、０以上の整数を示す。ｍ及びｎが異なるものの混合物であってもよい。ｋは、ヒドロキシ基の結合個数である１〜３の整数を示す。ｘは、Ｒ_２の結合個数である「Ａｒ_１の結合可能な個数−（ｋ＋２）」を示し、例えば、Ａｒ_１がベンゼン構造を示すときは（４−ｋ）、ナフタレン構造を示すときは（６−ｋ）、ビフェニレン構造を示すときは（８−ｋ）を示す。ｙは、各々独立して０〜４の整数を示す。

In formula (9), Ar ₁ represents an aromatic ring structure, and each R ₁ independently represents a methylene group, a methyleneoxy group, a methyleneoxymethylene group, an oxymethylene group, or a group in which these are connected. Show. R ₂ represents each independently a monovalent substituent hydrogen atom, alkyl group, or aryl group, and R ₃ each independently represents an alkyl group having 1 to 3 carbon atoms, an aryl group, a hydroxy group, or A hydroxymethylene group is shown. m represents an integer of 1 or more, and n represents an integer of 0 or more. A mixture of different m and n may be used. k represents an integer of 1 to 3, which is the number of bonded hydroxy groups. x represents “the number of bonds of Ar ₁ − (k + 2)”, which is the number of bonds of R _2. For example, when Ar ₁ represents a benzene structure (4-k), when it represents a naphthalene structure ( 6-k) and (8-k) when showing a biphenylene structure. y independently represents an integer of 0 to 4.

  In the above formula (9), the arrangement of each repeating unit is arbitrary. That is, the compound of the formula (9) may be a random copolymer or a block copolymer. The upper limit value of m is preferably 50 or less, more preferably 20 or less, and the upper limit value of n is preferably 20 or less.

  The main product of the modified naphthalene formaldehyde resin is a product in which formaldehyde becomes a methylene group at the time of modification, and the aromatic rings of the naphthalene ring and / or the hydroxy-substituted aromatic compound are bonded via the methylene group. The modified naphthalene formaldehyde resin obtained after modification is a mixture of many compounds because the position where formaldehyde is bonded to the naphthalene ring and the aromatic ring of the hydroxy-substituted aromatic compound, the position where the hydroxy group is bonded, the number of polymerization, etc. do not match. As obtained.

  From the viewpoint of solvent solubility, the OH value of the modified naphthalene formaldehyde resin is preferably 140 to 560 mgKOH / g, more preferably 160 to 470 mgKOH / g. The OH value is obtained based on JIS-K1557-1.

[Cyanate ester compound and production method thereof]
The cyanate ester compound of this embodiment can be obtained by cyanating the hydroxy group of the modified naphthalene formaldehyde resin. The cyanating method is not particularly limited, and a known method can be applied. Specifically, a method in which a modified naphthalene formaldehyde resin and cyanogen halide are reacted in a solvent in the presence of a basic compound. In the solvent, in the presence of a base, the cyanogen halide is always present in excess in excess of the base. Thus, the modified naphthalene formaldehyde resin is reacted with cyanogen halide (US Pat. No. 3,553,244), or a tertiary amine is used as a base, and this is used in excess of the cyanogen halide. In the presence, after adding a tertiary amine, a cyanide halide is added dropwise, or a method in which a cyanide halide and a tertiary amine are added dropwise (Patent No. 3319061), a continuous plug flow method, a modified naphthalene formaldehyde resin , Reacting with trialkylamine and cyanogen halide Method (Patent No. 3905559), treating tert-ammonium halide by-produced when a modified naphthalene formaldehyde resin and cyanogen halide are reacted in a non-aqueous solution in the presence of tert-amine with a cation and anion exchange pair Method (Patent No. 40552210), a modified naphthalene formaldehyde resin, in the presence of water and a solvent that can be separated, a tertiary amine and a cyanogen halide are added and reacted at the same time, and then washed with water and separated. A method of precipitation purification using a secondary or tertiary alcohol or a hydrocarbon poor solvent from the resulting solution (Japanese Patent No. 299954), and further, naphthols, cyanogen halide and tertiary amine are mixed with water and organic According to a method of reacting in a two-phase solvent with a solvent under acidic conditions (Japanese Patent No. 5026727) , Can be obtained cyanate ester compound of the present embodiment.

  When using the above-mentioned method in which the modified naphthalene formaldehyde resin and cyanide halide are reacted in the presence of a basic compound in a solvent, the modified naphthalene formaldehyde resin as a reaction substrate is either a cyanogen halide solution or a basic compound solution. After being dissolved in advance, the cyanogen halide solution and the basic compound solution are brought into contact with each other. The method for bringing the cyanogen halide solution into contact with the basic compound solution is not particularly limited. For example, (A) a method in which the basic compound solution is poured into the stirred cyanogen halide solution, (B ) A method in which a cyan halide solution is poured into a stirred basic compound solution, and a method (C) in which a cyan halide solution and a basic compound solution are continuously or alternately supplied. It is done.

  Among the methods (A) to (C), side reactions are suppressed, and a higher purity cyanate ester compound can be obtained in a high yield. Therefore, the method (A) is preferable.

  Moreover, the contact method of the said cyanogen halide solution and a basic compound solution can be performed either in a semi-batch format or a continuous flow format.

  In particular, when the method (A) is used, the reaction can be completed without leaving the hydroxy group of the modified naphthalene formaldehyde resin, and a higher purity cyanate compound can be obtained in a high yield. Since it can do, it is preferable to divide and drop a basic compound. The number of divisions is not particularly limited, but is preferably 1 to 5 times. In addition, the type of basic compound may be the same or different for each division.

  Examples of the cyanogen halide in this embodiment include cyanogen chloride and cyanogen bromide. As the cyanide halide, a cyanide halide obtained by a known production method such as a method of reacting hydrogen cyanide or metal cyanide with halogen may be used, or a commercially available product may be used. In addition, a reaction liquid containing cyanogen halide obtained by reacting hydrogen cyanide or metal cyanide with halogen can be used as it is.

  The amount of cyanogen halide used in the cyanate-forming step with respect to the modified naphthalene formaldehyde resin is preferably 0.5 mol or more and 5.0 mol or less, more preferably 1. It is 0 mol or more and 3.5 mol or less. The reason is to increase the yield of the cyanate ester compound without leaving unreacted modified naphthalene formaldehyde resin.

  The solvent used in the cyanogen halide solution is not particularly limited. For example, ketone solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; fats such as n-hexane, cyclohexane, isooctane, cyclohexanone, cyclopentanone, and 2-butanone Aromatic solvents such as benzene, toluene, xylene; ether solvents such as diethyl ether, dimethyl cellosolve, diglyme, tetrahydrofuran, methyltetrahydrofuran, dioxane, tetraethylene glycol dimethyl ether; dichloromethane, chloroform, carbon tetrachloride, Halogenated hydrocarbon solvents such as dichloroethane, trichloroethane, chlorobenzene, and bromobenzene; methanol, ethanol, isopropanol, methylsolvosolve, propylene Alcohol solvents such as N-glycol monomethyl ether; aprotic polar solvents such as N, N-dimethylformamide, N-methylpyrrolidone, 1,3-dimethyl-2-imidazolidone and dimethyl sulfoxide; nitriles such as acetonitrile and benzonitrile Solvents: Nitro solvents such as nitromethane and nitrobenzene; ester solvents such as ethyl acetate and ethyl benzoate; hydrocarbon solvents such as cyclohexane; water solvents can be used. Can be used alone or in combination of two or more.

  As the basic compound used in the cyanate formation step, either an organic base or an inorganic base can be used.

  Organic bases include trimethylamine, triethylamine, tri-n-butylamine, triamylamine, diisopropylethylamine, diethyl-n-butylamine, methyldi-n-butylamine, methylethyl-n-butylamine, dodecyldimethylamine, tribenzylamine, Ethanolamine, N, N-dimethylaniline, N, N-diethylaniline, diphenylmethylamine, pyridine, diethylcyclohexylamine, tricyclohexylamine, 1,4-diazabicyclo [2.2.2] octane, 1,8-diazabicyclo Tertiary amines such as [5.4.0] -7-undecene and 1,5-diazabicyclo [4.3.0] -5-nonene are preferred. Among these, trimethylamine, triethylamine, tri-n-butylamine, and diisopropylethylamine are more preferable, and triethylamine is more preferable because the target product can be obtained with high yield.

  The amount of the organic base used is preferably 0.1 mol or more and 8.0 mol or less, more preferably 1.0 mol or more and 3.5 mol or less, with respect to 1 mol of the hydroxy group of the phenol resin. The reason is to increase the yield of the cyanate ester compound without leaving unreacted modified naphthalene formaldehyde resin.

  As the inorganic base, an alkali metal hydroxide is preferable. Although it does not specifically limit as a hydroxide of an alkali metal, For example, sodium hydroxide, potassium hydroxide, and lithium hydroxide generally used industrially are mentioned. Sodium hydroxide is more preferable because it can be obtained at low cost.

  The amount of the inorganic base used is preferably 1.0 mol or more and 5.0 mol or less, more preferably 1.0 mol or more and 3.5 mol or less with respect to 1 mol of the hydroxy group of the modified naphthalene formaldehyde resin. is there. The reason is to increase the yield of the cyanate ester compound without leaving unreacted modified naphthalene formaldehyde resin.

  In this reaction, the basic compound can be used as a solution dissolved in a solvent as described above. As the solvent, an organic solvent or water can be used.

  The amount of the solvent used for the basic compound solution is preferably 0.1 to 100 parts by mass with respect to 1 part by mass of the modified naphthalene formaldehyde resin when the modified naphthalene formaldehyde resin is dissolved in the basic compound solution. Yes, more preferably 0.5 parts by mass or more and 50 parts by mass or less. When the modified naphthalene formaldehyde resin is not dissolved in the basic compound solution, the amount is preferably 0.1 parts by mass or more and 100 parts by mass, more preferably 0.25 parts by mass or more and 50 parts by mass with respect to 1 part by mass of the basic compound. It is as follows.

  The organic solvent for dissolving the basic compound is preferably used when the basic compound is an organic base, for example, a ketone solvent such as acetone, methyl ethyl ketone, or methyl isobutyl ketone; an aromatic solvent such as benzene, toluene, xylene, or the like. Ether solvents such as diethyl ether, dimethyl cellosolve, diglyme, tetrahydrofuran, methyltetrahydrofuran, dioxane, tetraethylene glycol dimethyl ether; halogenated hydrocarbons such as dichloromethane, chloroform, carbon tetrachloride, dichloroethane, trichloroethane, chlorobenzene, bromobenzene Solvent: Alcohol solvents such as methanol, ethanol, isopropanol, methyl sorbol, propylene glycol monomethyl ether; N, N-dimethylformamide, N Aprotic polar solvents such as methylpyrrolidone, 1,3-dimethyl-2-imidazolidone and dimethyl sulfoxide; nitrile solvents such as acetonitrile and benzonitrile; nitro solvents such as nitromethane and nitrobenzene; ethyl acetate and ethyl benzoate, etc. Ester solvent: A hydrocarbon solvent such as cyclohexane can be appropriately selected according to the basic compound, the reaction substrate and the solvent used in the reaction. These can be used alone or in combination of two or more.

  The water for dissolving the basic compound is preferably used when the basic compound is an inorganic base, and is not particularly limited, and may be tap water, distilled water, or deionized water. . In order to efficiently obtain the target cyanate ester compound, it is preferable to use distilled water or deionized water with less impurities.

  When the solvent used for the basic compound solution is water, it is preferable to use a catalytic amount of an organic base as a surfactant from the viewpoint of securing the reaction rate. Of these, tertiary amines with few side reactions are preferred. The tertiary amine is not particularly limited. For example, any of alkylamine, arylamine, and cycloalkylamine may be used. Specifically, trimethylamine, triethylamine, tri-n-butylamine, triamylamine, diisopropylethylamine, diethyl-n -Butylamine, methyldi-n-butylamine, methylethyl-n-butylamine, dodecyldimethylamine, tribenzylamine, triethanolamine, N, N-dimethylaniline, N, N-diethylaniline, diphenylmethylamine, pyridine, diethylcyclohexyl Amine, tricyclohexylamine, 1,4-diazabicyclo [2.2.2] octane, 1,8-diazabicyclo [5.4.0] -7-undecene, 1,5-diazabicyclo [4.3.0]- 5 Nonene, and the like. Among these, trimethylamine, triethylamine, tri-n-butylamine, and diisopropylethylamine are more preferable, and triethylamine is more preferable because the target product can be obtained with high solubility and yield in water.

  The total amount of the solvent used in the cyanation step is 2.5 parts by mass or more and 100 parts by mass or less with respect to 1 part by mass of the modified naphthalene formaldehyde resin. Is preferable from the viewpoint of efficient production.

  In the cyanate formation step, the pH of the reaction solution is not particularly limited, but it is preferable to carry out the reaction while keeping the pH below 7. This is because by suppressing the pH to less than 7, production of by-products such as a polymer of imide carbonate and cyanate ester compound is suppressed, and the cyanate ester compound tends to be produced efficiently. In order to keep the pH of the reaction solution below 7, it is preferable to add an acid. As the method, an acid is added to the cyanogen halide solution immediately before the cyanation step, and a pH meter is used as needed during the reaction. However, it is preferable to add an acid to the reaction system so as to keep the pH below 7. Examples of the acid used at that time include inorganic acids such as hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid; and organic acids such as acetic acid, lactic acid, and propionic acid.

  The reaction temperature in the cyanation step is such that by-products such as imide carbonate, a polymer of cyanate ester compound, and dialkylcyanoamide, condensation of the reaction liquid, and cyanogen chloride when cyanogen chloride is used as cyanogen halide. From the viewpoint of suppressing volatilization, it is preferably -20 to + 50 ° C, more preferably -15 to 15 ° C, and further preferably -10 to 10 ° C.

  The reaction pressure in the cyanate formation step may be normal pressure or increased pressure. If necessary, an inert gas such as nitrogen, helium, or argon may be passed through the system.

  The reaction time is not particularly limited, but the pouring time when the contact method is (A) and (B) and the contact time when (C) are preferably 1 minute to 20 hours, preferably 3 minutes to 10 hours. Time is more preferred. Furthermore, it is preferable to stir while maintaining the reaction temperature for 10 minutes to 10 hours thereafter. By setting it as such a range, the target cyanate ester compound can be obtained economically and industrially advantageously.

  The degree of progress of the reaction in the cyanation step can be analyzed by liquid chromatography or IR spectrum method. Volatile components such as by-product dicyan and dialkylcyanoamide can be analyzed by gas chromatography.

  After completion of the reaction, the intended cyanate ester compound can be isolated by carrying out ordinary post-treatment operations and, if desired, separation / purification operations. Specifically, an organic solvent layer containing a cyanate ester compound is separated from the reaction solution, washed with water, concentrated, precipitated or crystallized, or washed with water and then replaced with a solvent. At the time of washing, in order to remove excess amines, a method using an acidic aqueous solution such as dilute hydrochloric acid is also employed. In order to remove water from the sufficiently washed reaction solution, a drying operation can be performed using a general method such as sodium sulfate or magnesium sulfate. At the time of concentration and solvent replacement, in order to suppress polymerization of the cyanate ester compound, the organic solvent is distilled off by heating to a temperature of 90 ° C. or lower under reduced pressure. In precipitation or crystallization, a solvent having low solubility can be used. For example, an ether solvent, a hydrocarbon solvent such as hexane, or an alcohol solvent may be dropped into the reaction solution, or a reverse pouring method may be employed. In order to wash the obtained crude product, a method of washing the concentrate of the reaction solution and the precipitated crystals with an ether solvent, a hydrocarbon solvent such as hexane, or an alcohol solvent can be employed. The crystals obtained by concentrating the reaction solution can be dissolved again and then recrystallized. In the case of crystallization, the reaction solution may be simply concentrated or cooled. In addition, the purification method of the obtained cyanate ester compound will be described in detail later.

  Although the cyanate ester compound obtained by the said manufacturing method is not specifically limited, It can represent in following formula (1).

式（１）中、Ａｒ_１は、芳香環構造を示し、Ｒ_１は、各々独立にメチレン基、メチレンオキシ基、メチレンオキシメチレン基、若しくはオキシメチレン基、又はこれらが連結していているものを示す。Ｒ_２は、各々独立に一価の置換基である水素原子、アルキル基、又はアリール基を示し、Ｒ_３は、各々独立に炭素数が１〜３のアルキル基、アリール基、ヒドロキシ基、又はヒドロキシメチレン基を示し、ｍは、１以上の整数を示し、ｎは、０以上の整数を示す。ｍ及びｎが異なる化合物の混合物であってもよい。各繰り返し単位の配列は任意である。ｋは、シアナト基の結合個数である１〜３の整数を示す。ｘは、Ｒ_２の結合個数である「Ａｒ_１の結合可能な個数−（ｋ＋２）」の整数を示す。例えば、Ａｒ_１がベンゼン構造を示すときは（４−ｋ）、ナフタレン構造を示すときは（６−ｋ）、ビフェニレン構造を示すときは（８−ｋ）を示す。ｙは、各々独立して０〜４の整数を示す。

In formula (1), Ar ₁ represents an aromatic ring structure, and each R ₁ independently represents a methylene group, a methyleneoxy group, a methyleneoxymethylene group, an oxymethylene group, or a group in which these are connected. Show. R ₂ represents each independently a monovalent substituent hydrogen atom, alkyl group, or aryl group, and R ₃ each independently represents an alkyl group having 1 to 3 carbon atoms, an aryl group, a hydroxy group, or Represents a hydroxymethylene group, m represents an integer of 1 or more, and n represents an integer of 0 or more. It may be a mixture of compounds in which m and n are different. The arrangement of each repeating unit is arbitrary. k represents an integer of 1 to 3, which is the number of cyanate groups bonded. x represents an integer of “number of bonds of Ar ₁ − (k + 2)”, which is the number of bonds of R ₂ . For example, when Ar ₁ shows a benzene structure, it shows (4-k), when it shows a naphthalene structure (6-k), and when it shows a biphenylene structure, it shows (8-k). y independently represents an integer of 0 to 4.

  In the above formula (1), the arrangement of each repeating unit is arbitrary, and the compound represented by the formula (1) may be a random copolymer or a block copolymer. The upper limit value of m is preferably 50 or less, more preferably 20 or less, and the upper limit value of n is preferably 20 or less.

  For example, a cyanate ester compound obtained by reacting a naphthol-modified naphthalene formaldehyde resin described in Synthesis Example 1 described later and cyanogen halide in a solvent in the presence of a basic compound is represented by the following formula (10). This is a mixture of cyanate esters whose representative composition is a group of compounds.

  The weight average molecular weight (Mw) of the cyanate ester compound of the present embodiment is not particularly limited, but is preferably 200 or more and 25000 or less, more preferably 250 or more and 20000 or less, and further preferably 300 or more and 15000 or less. is there.

  The obtained cyanate ester compound can be identified by a known method such as NMR. The purity of the cyanate ester compound can be analyzed by liquid chromatography or IR spectroscopy. Byproducts such as dialkylcyanoamide in the cyanate ester compound and volatile components such as residual solvent can be quantitatively analyzed by gas chromatography. Halogen compounds remaining in the cyanate ester compound can be identified by a liquid chromatograph mass spectrometer, and can be quantitatively analyzed by potentiometric titration using a silver nitrate solution or ion chromatography after decomposition by a combustion method. . The polymerization reactivity of the cyanate ester compound can be evaluated by gelation time by a hot plate method or a torque measurement method.

[Purification method of cyanate ester compound]
The cyanate ester compound may be further purified as necessary to further improve the purity and reduce the amount of remaining metal. Further, when the acid catalyst and the cocatalyst remain, generally, the storage stability of the composition for forming the lower layer film is lowered, or when the basic catalyst remains, the sensitivity of the composition for forming the lower layer film is generally lowered. Purification for the purpose of reduction may be performed.

  Purification can be performed by a known method as long as the cyanate ester compound is not modified, and is not particularly limited. For example, a method of washing with water, a method of washing with an acidic aqueous solution, a method of washing with a basic aqueous solution, ion exchange The method of processing with resin and the method of processing with silica gel column chromatography are mentioned. These purification methods may be performed singly or in combination of two or more. Moreover, the purification method which wash | cleans with acidic aqueous solution is mentioned later.

  Acidic aqueous solution, basic aqueous solution, ion exchange resin, and silica gel column chromatography are optimal depending on the metal to be removed, the amount and type of acidic compound and / or basic compound, the type of cyanate ester compound to be purified, etc. It is possible to select appropriately. For example, as an acidic aqueous solution, a hydrochloric acid, nitric acid, acetic acid aqueous solution having a concentration of 0.01 to 10 mol / L, an aqueous ammonia solution having a concentration of 0.01 to 10 mol / L as a basic aqueous solution, a cation exchange resin ( For example, Organo Amberlyst 15J-HG Dry) may be mentioned.

  You may dry after the said refinement | purification. Drying can be performed by a known method, and is not particularly limited, and examples thereof include a method of vacuum drying and hot air drying under conditions where the cyanate ester compound is not denatured.

[Purification method of washing with acidic aqueous solution]
The method of purifying the cyanate ester compound by washing with an acidic aqueous solution is, for example, as follows. The metal contained in the solution (B) containing the cyanate ester compound and the organic solvent is obtained by dissolving the cyanate ester compound in an organic solvent that is arbitrarily immiscible with water and bringing the solution into contact with an acidic aqueous solution and performing an extraction treatment. A step of separating the organic phase and the aqueous phase after transferring the water component to the aqueous phase. By this purification, the content of various metals in the composition for forming a lower layer film for lithography of the present embodiment can be significantly reduced.

  The organic solvent that is not arbitrarily mixed with water is not particularly limited, but an organic solvent that can be safely applied to a semiconductor manufacturing process is preferable. The amount of the organic solvent to be used is preferably 1.0 to 100 times by mass with respect to the cyanate ester compound to be used.

  Specific examples of the organic solvent used include, for example, ethers such as diethyl ether and diisopropyl ether, esters such as ethyl acetate, n-butyl acetate and isoamyl acetate; methyl ethyl ketone, methyl isobutyl ketone, ethyl isobutyl ketone, cyclohexanone, Ketones such as cyclopentanone, 2-heptanone, 2-pentanone; glycol ether acetates such as ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monoethyl ether acetate Aliphatic hydrocarbons such as n-hexane and n-heptane; aromatic hydrocarbons such as toluene and xylene; methylene chloride, chloroform, etc. And halogenated hydrocarbons. Among these, toluene, 2-heptanone, cyclohexanone, cyclopentanone, methyl isobutyl ketone, propylene glycol monomethyl ether acetate, and ethyl acetate are preferable, and cyclohexanone and propylene glycol monomethyl ether acetate are more preferable. These organic solvents can be used alone or in a mixture of two or more.

  The acidic aqueous solution is appropriately selected from aqueous solutions in which generally known organic and inorganic compounds are dissolved in water. For example, an aqueous solution in which a mineral acid such as hydrochloric acid, sulfuric acid, nitric acid or phosphoric acid is dissolved in water, or acetic acid, propionic acid, succinic acid, malonic acid, succinic acid, fumaric acid, maleic acid, tartaric acid, citric acid, methanesulfone An aqueous solution in which an organic acid such as acid, phenolsulfonic acid, p-toluenesulfonic acid, trifluoroacetic acid or the like is dissolved in water can be used. These acidic aqueous solutions can be used alone or in combination of two or more. Among these acidic aqueous solutions, aqueous solutions of sulfuric acid, nitric acid, and carboxylic acids such as acetic acid, oxalic acid, tartaric acid, and citric acid are preferable, and aqueous solutions of sulfuric acid, succinic acid, tartaric acid, and citric acid are preferable, and an aqueous solution of succinic acid is particularly preferable. . Since polyvalent carboxylic acids such as succinic acid, tartaric acid, and citric acid are coordinated to metal ions to produce a chelate effect, it is considered that the metal can be removed more. Moreover, the water used here is preferably one having a low metal content, such as ion-exchanged water, for the purpose of the present invention.

  The pH of the acidic aqueous solution is not particularly limited, but if the acidity of the aqueous solution becomes too large, it may adversely affect the compound or resin used, which is not preferable. The pH range is preferably about 0 to 5, more preferably about pH 0 to 3.

  The amount of the acidic aqueous solution used is not particularly limited. However, if the amount is too small, it is necessary to increase the number of extractions for removing the metal. Conversely, if the amount of the aqueous solution is too large, the total amount of the liquid increases. The above problems may occur. The amount of the aqueous solution used is preferably 10% by mass or more and 200% by mass or less, and more preferably 20-100% by mass, with respect to the cyanate ester compound solution (100% by mass).

  A metal component is extracted by bringing the acidic aqueous solution into contact with a solution (B) containing an organic solvent which is not arbitrarily miscible with the cyanate ester compound and water.

  The temperature at the time of performing the extraction treatment is preferably in the range of 20 to 90 ° C, more preferably in the range of 30 to 80 ° C. The extraction operation is performed, for example, by mixing the mixture well by stirring or the like and then allowing it to stand. Thereby, the metal component contained in the solution containing the compound to be used and the organic solvent is transferred to the aqueous phase. Further, this operation tends to reduce the acidity of the solution and suppress the alteration of the compound used.

  After the extraction treatment, the solution is separated into a solution phase containing the compound to be used and an organic solvent and an aqueous phase, and a solution containing the organic solvent is recovered by decantation or the like. The standing time is not particularly limited. However, if the standing time is too short, the separation between the solution phase containing the organic solvent and the aqueous phase is not preferable. Usually, the time to stand still is 1 minute or more, More preferably, it is 10 minutes or more, More preferably, it is 30 minutes or more. The extraction process may be performed only once, but it is also effective to repeat the operations of mixing, standing, and separation a plurality of times.

  When such an extraction treatment is performed using an acidic aqueous solution, it is preferable that the solution containing the organic solvent extracted from the aqueous solution after the treatment is further subjected to an extraction treatment with water. . The extraction operation is performed by allowing the mixture to stand after mixing well by stirring or the like. And since the obtained solution isolate | separates into the solution phase containing a compound and an organic solvent, and an aqueous phase, a solution phase is collect | recovered by decantation etc. Moreover, the water used here is preferably one having a low metal content, such as ion-exchanged water, for the purpose of the present invention. The extraction process may be performed only once, but it is also effective to repeat the operations of mixing, standing, and separation a plurality of times. In addition, the use ratio of both in the extraction process, conditions such as temperature and time are not particularly limited, but may be the same as in the case of the contact process with the acidic aqueous solution.

  The water thus mixed in the solution containing the compound and the organic solvent can be easily removed by performing an operation such as vacuum distillation. If necessary, an organic solvent can be added to adjust the concentration of the compound to an arbitrary concentration.

  A method for obtaining only the compound from the obtained solution containing an organic solvent can be performed by a known method such as removal under reduced pressure, separation by reprecipitation, and a combination thereof. If necessary, known processes such as a concentration operation, a filtration operation, a centrifugal separation operation, and a drying operation can be performed.

[Material for forming lower layer film for lithography]
The material for forming a lower layer film for lithography of this embodiment contains a cyanate ester compound obtained by cyanating the modified naphthalene formaldehyde resin. The material for forming a lower layer film for lithography of the present embodiment includes a cyanate ester compound other than the above-mentioned cyanate ester compound, a known material for forming a lower layer film for lithography, and the like as long as desired characteristics are not impaired. May be included.

  In the material for forming a lower layer film for lithography of the present embodiment, the content of the cyanate ester compound is 50% with respect to the total amount (100% by weight) of the material for forming the lower layer film from the viewpoint of heat resistance and etching resistance. % To 100% by mass, more preferably 70% to 100% by mass, and still more preferably 90% to 100% by mass. Further, in the material for forming a lower layer film for lithography of the present embodiment, it is more preferable that the cyanate ester compound is 100% by mass because the decrease in thermal weight is small.

  The cyanate ester compound of this embodiment is preferably a compound represented by the following formula (1).

式（１）中、Ａｒ_１、Ｒ_１、Ｒ_２、Ｒ_３、ｋ、ｍ、ｎ、ｘ、及びｙは、上記と同義である。

In the formula (1), Ar ₁ , R ₁ , R ₂ , R ₃ , k, m, n, x, and y are as defined above.

Cyanate ester compound of the present embodiment, when Ar ₁ in the above formula (1) indicates a naphthalene structure, i.e., it is, etch resistance and material availability are compounds represented by the following formula (1-1) It is preferable at the point.

式（１−１）中、Ｒ_１〜Ｒ_３、ｋ、ｍ、ｎ、及びｙは、上記式（１）で説明したものと同義であり、ｘは、（６−ｋ）の整数を示す。

In formula (1-1), R _{1 to} R ₃ , k, m, n, and y have the same meaning as described in formula (1) above, and x represents an integer of (6-k). .

  The compound represented by the above formula (1-1) is preferably a compound represented by the following formula (1-2) from the viewpoint of raw material availability.

上記式（１−２）中、Ｒ_１、ｍ、及びｎは、上記式（１）で説明したものと同義である。

In said formula (1-2), R < ₁ >, m, and n are synonymous with what was demonstrated by said formula (1).

[Composition for forming underlayer film for lithography]
The composition for forming a lower layer film for lithography of the present embodiment contains the material for forming a lower layer film for lithography containing the above-described cyanate ester compound and a solvent.

[solvent]
As the solvent used in the composition for forming a lower layer film for lithography of the present embodiment, a known one can be appropriately used as long as it can dissolve at least the cyanate ester compound. Specific examples of the solvent include, for example, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; cellosolv solvents such as propylene glycol monomethyl ether and propylene glycol monomethyl ether acetate; ethyl lactate, methyl acetate, ethyl acetate, and acetic acid Ester solvents such as butyl, isoamyl acetate, ethyl lactate, methyl methoxypropionate, methyl hydroxyisobutyrate; alcohol solvents such as methanol, ethanol, isopropanol, 1-ethoxy-2-propanol; toluene, xylene, anisole, etc. Although aromatic hydrocarbon is mentioned, it is not specifically limited to these. These solvents can be used alone or in combination of two or more.

  Among the above solvents, cyclohexanone, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethyl lactate, methyl hydroxyisobutyrate, and anisole are particularly preferable from the viewpoint of safety.

  The content of the solvent in the case of containing the solvent is not particularly limited, but from the viewpoint of solubility and film formation, 25 parts by mass or more with respect to 100 parts by mass of the lower layer film-forming material containing a cyanate ester compound. It is preferably 9900 parts by mass or less, more preferably 900 parts by mass or more and 4,900 parts by mass or less.

  The composition for forming a lower layer film for lithography of the present embodiment may contain an acid generator, a crosslinking agent, an acid generator, and other components as required in addition to the cyanate ester compound and the solvent. Hereinafter, these optional components will be described.

  The composition for forming a lower layer film for lithography of the present embodiment may further contain a crosslinking agent as necessary from the viewpoint of suppressing intermixing. Specific examples of the crosslinking agent that can be used in this embodiment include double bonds such as melamine compounds, guanamine compounds, glycoluril compounds, urea compounds, epoxy compounds, thioepoxy compounds, isocyanate compounds, azide compounds, alkenyl ether groups, and the like. And a compound having at least one group selected from a methylol group, an alkoxymethyl group, and an acyloxymethyl group as a substituent (crosslinkable group), but is not particularly limited thereto. In addition, these crosslinking agents can be used individually by 1 type or in combination of 2 or more types. Moreover, you may use these as an additive. The crosslinkable group may be introduced as a pendant group into the compound represented by the formula (1). A compound containing a hydroxy group can also be used as a crosslinking agent.

  Specific examples of the melamine compound include, for example, hexamethylol melamine, hexamethoxymethyl melamine, a compound in which 1 to 6 methylol groups of hexamethylol melamine are methoxymethylated, or a mixture thereof, hexamethoxyethyl melamine, hexaacyloxymethyl melamine And compounds in which 1 to 6 methylol groups of hexamethylolmelamine are acyloxymethylated, or a mixture thereof. Specific examples of the epoxy compound include tris (2,3-epoxypropyl) isocyanurate, trimethylolmethane triglycidyl ether, trimethylolpropane triglycidyl ether, and triethylolethane triglycidyl ether.

  Specific examples of the guanamine compound include, for example, tetramethylolguanamine, tetramethoxymethylguanamine, a compound in which 1 to 4 methylol groups of tetramethylolguanamine are methoxymethylated, or a mixture thereof, tetramethoxyethylguanamine, tetraacyloxyguanamine, And a compound in which 1 to 4 methylol groups of tetramethylolguanamine are acyloxymethylated, or a mixture thereof. Specific examples of the glycoluril compound include, for example, tetramethylol glycoluril, tetramethoxyglycoluril, tetramethoxymethylglycoluril, a compound in which 1 to 4 methylol groups of tetramethylolglycoluril are methoxymethylated, or a mixture thereof, and Examples thereof include compounds in which 1 to 4 methylol groups of tetramethylol glycoluril are acyloxymethylated or a mixture thereof. Specific examples of the urea compound include, for example, tetramethylol urea, tetramethoxymethyl urea, a compound in which 1 to 4 methylol groups of tetramethylol urea are methoxymethylated, or a mixture thereof, and tetramethoxyethyl urea.

  Specific examples of the compound containing an alkenyl ether group include, for example, ethylene glycol divinyl ether, triethylene glycol divinyl ether, 1,2-propanediol divinyl ether, 1,4-butanediol divinyl ether, tetramethylene glycol divinyl ether, neo Pentyl glycol divinyl ether, trimethylolpropane trivinyl ether, hexanediol divinyl ether, 1,4-cyclohexanediol divinyl ether, pentaerythritol trivinyl ether, pentaerythritol tetravinyl ether, sorbitol tetravinyl ether, sorbitol pentavinyl ether, and trimethylolpropane trivinyl ether Can be mentioned.

  In the composition for forming a lower layer film for lithography of the present embodiment, the content of the crosslinking agent is not particularly limited, but is 0.0 part by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the cyanate ester compound. Is more preferably 0.0 part by mass or more and 40 parts by mass or less. By setting it as the above preferable range, the occurrence of the mixing phenomenon with the resist layer tends to be suppressed, the antireflection effect is enhanced, and the film forming property after crosslinking tends to be enhanced.

  The composition for forming a lower layer film for lithography of the present embodiment may further contain an acid generator as necessary from the viewpoint of further promoting the crosslinking reaction by heat. As the acid generator, those that generate an acid by thermal decomposition and those that generate an acid by light irradiation are known, and any of them can be used.

As an acid generator, for example,
1) An onium salt represented by the following general formula (P1a-1), (P1a-2), (P1a-3) or (P1b),
2) a diazomethane derivative represented by the following general formula (P2),
3) a glyoxime derivative represented by the following general formula (P3),
4) A bissulfone derivative represented by the following general formula (P4),
5) A sulfonic acid ester of an N-hydroxyimide compound represented by the following general formula (P5),
6) β-ketosulfonic acid derivative,
7) a disulfone derivative,
8) Nitrobenzyl sulfonate derivative,
9) Sulfonate derivatives are mentioned, but not limited thereto. In addition, these acid generators can be used individually by 1 type or in combination of 2 or more types.

式中、Ｒ^101a、Ｒ^101b、及びＲ^101cは、各々独立に炭素数１〜１２の直鎖状、分岐状若しくは環状のアルキル基、アルケニル基、オキソアルキル基又はオキソアルケニル基；炭素数６〜２０のアリール基；又は炭素数７〜１２のアラルキル基若しくはアリールオキソアルキル基を示し、これらの基の水素原子の一部又は全部がアルコキシ基等によって置換されていてもよい。また、Ｒ^101bとＲ^101cとは環を形成してもよく、環を形成する場合には、Ｒ^101b、及びＲ^101cは、各々独立に炭素数１〜６のアルキレン基を示す。Ｋ^-は、非求核性対向イオンを示す。Ｒ^101d、Ｒ^101e、Ｒ^101f、及びＲ^101gは、各々独立にＲ^101a、Ｒ^101b、及びＲ^101cに水素原子を加えて示される。Ｒ^101dとＲ^101eと、及びＲ^101dとＲ^101eとＲ^101fとは環を形成してもよく、環を形成する場合には、Ｒ^101dとＲ^101eと、及びＲ^101dとＲ^101eとＲ^101fとは炭素数３〜１０のアルキレン基を示し、又は、式中の窒素原子を環の中に有する複素芳香族環を示す。

In the formula, each of R ^101a , R ^101b , and R ^101c is independently a linear, branched, or cyclic alkyl group, alkenyl group, oxoalkyl group, or oxoalkenyl group having 1 to 12 carbon atoms; 20 aryl group; or an aralkyl group or aryloxoalkyl group having 7 to 12 carbon atoms, part or all of hydrogen atoms of these groups may be substituted with an alkoxy group or the like. R ^101b and R ^101c may form a ring. When a ring is formed, R ^101b and R ^101c each independently represent an alkylene group having 1 to 6 carbon atoms. K ⁻ represents a non-nucleophilic counter ion. R ^101d , R ^101e , R ^101f , and R ^101g are each independently represented by adding a hydrogen atom to R ^101a , R ^101b , and R ^101c . R ^101d and R ^101e , and R ^101d , R ^101e and R ^101f may form a ring. In the case of forming a ring, R ^101d and R ^101e , and R ^101d , R ^101e and R ^101f And represents an alkylene group having 3 to 10 carbon atoms, or a heteroaromatic ring having a nitrogen atom in the formula.

R ^101a , R ^101b , R ^101c , R ^101d , R ^101e , R ^101f , and R ^101g may be the same as or different from each other. Specific alkyl groups include, but are not limited to, for example, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group, heptyl Group, octyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclopropylmethyl group, 4-methylcyclohexyl group, cyclohexylmethyl group, norbornyl group, and adamantyl group. Examples of the alkenyl group include, but are not limited to, a vinyl group, an allyl group, a propenyl group, a butenyl group, a hexenyl group, and a cyclohexenyl group. Examples of the oxoalkyl group include, but are not limited to, 2-oxocyclopentyl group, 2-oxocyclohexyl group, 2-oxopropyl group, 2-cyclopentyl-2-oxoethyl group, 2-cyclohexyl-2-oxoethyl, and the like. And a 2- (4-methylcyclohexyl) -2-oxoethyl group. Examples of the oxoalkenyl group include, but are not limited to, a 2-oxo-4-cyclohexenyl group and a 2-oxo-4-propenyl group. Examples of the aryl group include, but are not limited to, phenyl group, naphthyl group, p-methoxyphenyl group, m-methoxyphenyl group, o-methoxyphenyl group, ethoxyphenyl group, p-tert-butoxyphenyl group. , Alkoxyphenyl groups such as m-tert-butoxyphenyl group; 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, ethylphenyl group, 4-tert-butylphenyl group, 4-butylphenyl group, Alkylphenyl groups such as dimethylphenyl group; alkyl naphthyl groups such as methyl naphthyl group and ethyl naphthyl group; alkoxy naphthyl groups such as methoxy naphthyl group and ethoxy naphthyl group; dialkyl naphthyl groups such as dimethyl naphthyl group and diethyl naphthyl group; Group and diethoxyna It includes dialkoxy naphthyl group such as a methyl group. Examples of the aralkyl group include, but are not limited to, a benzyl group, a phenylethyl group, and a phenethyl group. Examples of the aryloxoalkyl group include, but are not limited to, 2-phenyl-2-oxoethyl group, 2- (1-naphthyl) -2-oxoethyl group, 2- (2-naphthyl) -2-oxoethyl group, and the like. And 2-aryl-2-oxoethyl group. Examples of the non-nucleophilic counter ion of K ⁻ include, but are not limited to, halide ions such as chloride ion and bromide ion; triflate, 1,1,1-trifluoroethanesulfonate, nonafluorobutanesulfonate, and the like. And aryl sulfonates such as tosylate, benzene sulfonate, 4-fluorobenzene sulfonate, 1,2,3,4,5-pentafluorobenzene sulfonate; alkyl sulfonates such as mesylate and butane sulfonate.

When R ^101d , R ^101e , R ^101f , and R ^101g represent a heteroaromatic ring having a nitrogen atom in the formula, examples of the heteroaromatic ring include imidazole derivatives (for example, imidazole derivatives). 4-methylimidazole, 4-methyl-2-phenylimidazole, etc.), pyrazole derivatives, furazane derivatives, pyrroline derivatives (eg pyrroline, 2-methyl-1-pyrroline etc.), pyrrolidine derivatives (eg pyrrolidine, N-methylpyrrolidine, Pyrrolidinone, N-methylpyrrolidone, etc.), imidazoline derivatives, imidazolidine derivatives, pyridine derivatives (eg pyridine, methylpyridine, ethylpyridine, propylpyridine, butylpyridine, 4- (1-butylpentyl) pyridine, dimethylpyridine, trimethylpyridine, Triethylpyridine, Phenylpyridine, 3-methyl-2-phenylpyridine, 4-tert-butylpyridine, diphenylpyridine, benzylpyridine, methoxypyridine, butoxypyridine, dimethoxypyridine, 1-methyl-2-pyridone, 4-pyrrolidinopyridine, 1-methyl -4-phenylpyridine, 2- (1-ethylpropyl) pyridine, aminopyridine, dimethylaminopyridine, etc.), pyridazine derivatives, pyrimidine derivatives, pyrazine derivatives, pyrazoline derivatives, pyrazolidine derivatives, piperidine derivatives, piperazine derivatives, morpholine derivatives, indoles Derivatives, isoindole derivatives, 1H-indazole derivatives, indoline derivatives, quinoline derivatives (eg quinoline, 3-quinolinecarbonitrile, etc.), isoquinoline derivatives, cinnoline derivatives Quinazoline derivative, quinoxaline derivative, phthalazine derivative, purine derivative, pteridine derivative, carbazole derivative, phenanthridine derivative, acridine derivative, phenazine derivative, 1,10-phenanthroline derivative, adenine derivative, adenosine derivative, guanine derivative, guanosine derivative, uracil Derivatives and uridine derivatives are exemplified.

  The onium salt represented by the above formula (P1a-1) and formula (P1a-2) has a function as a photoacid generator and a thermal acid generator. The onium salt represented by the above formula (P1a-3) has a function as a thermal acid generator.

式（Ｐ１ｂ）中、Ｒ^102a、及びＲ^102bは、各々独立に炭素数１〜８の直鎖状、分岐状又は環状のアルキル基を示す。Ｒ¹⁰³は、炭素数１〜１０の直鎖状、分岐状又は環状のアルキレン基を示す。Ｒ^104a、及びＲ^104bは、各々独立に炭素数３〜７の２−オキソアルキル基を示す。Ｋ^-は非求核性対向イオンを示す。

In the formula (P1b), R ^102a and R ^102b each independently represent a linear, branched or cyclic alkyl group having 1 to 8 carbon atoms. R ¹⁰³ represents a linear, branched or cyclic alkylene group having 1 to 10 carbon atoms. R ^104a and R ^104b each independently represent a 3-oxoalkyl group having 3 to 7 carbon atoms. K ⁻ represents a non-nucleophilic counter ion.

Specific examples of R ^102a and R ^102b are not limited to the following, but are each independently a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, or a tert-butyl group. Pentyl group, hexyl group, heptyl group, octyl group, cyclopentyl group, cyclohexyl group, cyclopropylmethyl group, 4-methylcyclohexyl group, and cyclohexylmethyl group. Specific examples of R ¹⁰³ include, but are not limited to, methylene group, ethylene group, propylene group, butylene group, pentylene group, hexylene group, heptylene group, octylene group, nonylene group, 1,4-cyclohexylene. Group, 1,2-cyclohexylene group, 1,3-cyclopentylene group, 1,4-cyclooctylene group, and 1,4-cyclohexanedimethylene group. Specific examples of R ^104a and R ^104b include, but are not limited to, a 2-oxopropyl group, a 2-oxocyclopentyl group, a 2-oxocyclohexyl group, and a 2-oxocycloheptyl group. It is done. Examples of K ⁻ are the same as those described in the formulas (P1a-1), (P1a-2), and (P1a-3).

式（Ｐ２）中、Ｒ¹⁰⁵、Ｒ¹⁰⁶はそれぞれ独立して炭素数１〜１２の直鎖状、分岐状又は環状のアルキル基又はハロゲン化アルキル基、炭素数６〜２０のアリール基又はハロゲン化アリール基、又は炭素数７〜１２のアラルキル基を示す。

In formula (P2), R ¹⁰⁵ and R ¹⁰⁶ are each independently a linear, branched or cyclic alkyl group or halogenated alkyl group having 1 to 12 carbon atoms, an aryl group having 6 to 20 carbon atoms or a halogenated group. An aryl group or an aralkyl group having 7 to 12 carbon atoms is shown.

Examples of the alkyl group represented by R ¹⁰⁵ and R ¹⁰⁶ include, but are not limited to, for example, a poison t ratio, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert -A butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, an amyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a norbornyl group, and an adamantyl group. Examples of the halogenated alkyl group include, but are not limited to, a trifluoromethyl group, a 1,1,1-trifluoroethyl group, a 1,1,1-trichloroethyl group, and a nonafluorobutyl group. Examples of the aryl group include, but are not limited to, phenyl group, p-methoxyphenyl group, m-methoxyphenyl group, o-methoxyphenyl group, ethoxyphenyl group, p-tert-butoxyphenyl group, m-tert- Alkoxyphenyl groups such as butoxyphenyl group; 2-methylphenyl group, 3-methylphenyl group, 4-methylphenyl group, ethylphenyl group, 4-tert-butylphenyl group, 4-butylphenyl group, and dimethylphenyl group Of these alkylphenyl groups. Examples of the halogenated aryl group include, but are not limited to, a fluorophenyl group, a chlorophenyl group, and a 1,2,3,4,5-pentafluorophenyl group. Examples of the aralkyl group include, but are not limited to, a benzyl group and a phenethyl group.

式（Ｐ３）中、Ｒ¹⁰⁷、Ｒ¹⁰⁸、及びＲ¹⁰⁹は、各々独立に炭素数１〜１２の直鎖状、分岐状若しくは環状のアルキル基又はハロゲン化アルキル基；炭素数６〜２０のアリール基若しくはハロゲン化アリール基；又は炭素数７〜１２のアラルキル基を示す。Ｒ¹⁰⁸、及びＲ¹⁰⁹は互いに結合して環状構造を形成してもよく、環状構造を形成する場合、Ｒ¹⁰⁸、及びＲ¹⁰⁹は、各々独立に炭素数１〜６の直鎖状又は分岐状のアルキレン基を示す。

In formula (P3), R ¹⁰⁷ , R ¹⁰⁸ and R ¹⁰⁹ each independently represent a linear, branched or cyclic alkyl group or halogenated alkyl group having 1 to 12 carbon atoms; aryl having 6 to 20 carbon atoms Group or a halogenated aryl group; or an aralkyl group having 7 to 12 carbon atoms. R ¹⁰⁸ and R ¹⁰⁹ may be bonded to each other to form a cyclic structure. In the case of forming a cyclic structure, R ¹⁰⁸ and R ¹⁰⁹ are each independently a linear or branched group having 1 to 6 carbon atoms. Represents an alkylene group.

Examples of the alkyl group, halogenated alkyl group, aryl group, halogenated aryl group, and aralkyl group of R ¹⁰⁷ , R ¹⁰⁸ , and R ¹⁰⁹ include the same groups as those described for R ¹⁰⁵ and R ¹⁰⁶ . The alkylene group for R ¹⁰⁸ and R ¹⁰⁹ is not limited to the following, and examples thereof include a methylene group, an ethylene group, a propylene group, a butylene group, and a hexylene group.

式（Ｐ４）中、Ｒ^101a、Ｒ^101bは、上述したものと同様である。

In formula (P4), R ^101a and R ^101b are the same as those described above.

式（Ｐ５）中、Ｒ¹¹⁰は、炭素数６〜１０のアリーレン基、炭素数１〜６のアルキレン基又は炭素数２〜６のアルケニレン基を示す。これらの基の水素原子の一部又は全部は、さらに炭素数１〜４の直鎖状若しくは分岐状のアルキル基又はアルコキシ基、ニトロ基、アセチル基、又はフェニル基で置換されていてもよい。Ｒ¹¹¹は、炭素数１〜８の直鎖状、分岐状若しくは置換のアルキル基、アルケニル基又はアルコキシアルキル基、フェニル基、又はナフチル基を示す。これらの基の水素原子の一部又は全部は、さらに炭素数１〜４のアルキル基又はアルコキシ基、ニトロ基、アセチル基、又はフェニル基で置換されていてもよい。Ｒ¹¹¹は、炭素数１〜８の直鎖状、分岐状若しくは置換のアルキル基、アルケニル基又はアルコキシアルキル基、フェニル基、又はナフチル基を示す。これらの基の水素原子の一部又は全部は、さらに炭素数１〜４のアルキル基又はアルコキシ基；炭素数１〜４のアルキル基、アルコキシ基、ニトロ基又はアセチル基で置換されていてもよいフェニル基；炭素数３〜５のヘテロ芳香族基；又は塩素原子、フッ素原子で置換されていてもよい。

In formula (P5), R ¹¹⁰ represents an arylene group having 6 to 10 carbon atoms, an alkylene group having 1 to 6 carbon atoms, or an alkenylene group having 2 to 6 carbon atoms. Some or all of the hydrogen atoms of these groups may be further substituted with a linear or branched alkyl group having 1 to 4 carbon atoms, an alkoxy group, a nitro group, an acetyl group, or a phenyl group. R ¹¹¹ represents a linear, branched or substituted alkyl group, alkenyl group, alkoxyalkyl group, phenyl group, or naphthyl group having 1 to 8 carbon atoms. Some or all of the hydrogen atoms in these groups may be further substituted with an alkyl group or alkoxy group having 1 to 4 carbon atoms, a nitro group, an acetyl group, or a phenyl group. R ¹¹¹ represents a linear, branched or substituted alkyl group, alkenyl group, alkoxyalkyl group, phenyl group, or naphthyl group having 1 to 8 carbon atoms. Some or all of the hydrogen atoms in these groups may be further substituted with an alkyl group having 1 to 4 carbon atoms or an alkoxy group; an alkyl group having 1 to 4 carbon atoms, an alkoxy group, a nitro group, or an acetyl group. A phenyl group; a heteroaromatic group having 3 to 5 carbon atoms; or a chlorine atom or a fluorine atom.

Here, the arylene group of R ¹¹⁰ is not limited to the following, and examples thereof include a 1,2-phenylene group and a 1,8-naphthylene group. Examples of the alkylene group include, but are not limited to, a methylene group, an ethylene group, a trimethylene group, a tetramethylene group, a phenylethylene group, and a norbornane-2,3-diyl group. Examples of the alkenylene group include, but are not limited to, a 1,2-vinylene group, a 1-phenyl-1,2-vinylene group, and a 5-norbornene-2,3-diyl group. Examples of the alkyl group for R ¹¹¹ include the same groups as those described for R ^{101a to} R ^101c . Examples of the alkenyl group include, but are not limited to, vinyl group, 1-propenyl group, allyl group, 1-butenyl group, 3-butenyl group, isoprenyl group, 1-pentenyl group, 3-pentenyl group, 4-pentenyl group. Group, dimethylallyl group, 1-hexenyl group, 3-hexenyl group, 5-hexenyl group, 1-heptenyl group, 3-heptenyl group, 6-heptenyl group, and 7-octenyl group. Examples of the alkoxyalkyl group include, but are not limited to, for example, methoxymethyl group, ethoxymethyl group, propoxymethyl group, butoxymethyl group, pentyloxymethyl group, hexyloxymethyl group, heptyloxymethyl group, methoxyethyl group, Ethoxyethyl group, propoxyethyl group, butoxyethyl group, pentyloxyethyl group, hexyloxyethyl group, methoxypropyl group, ethoxypropyl group, propoxypropyl group, butoxypropyl group, methoxybutyl group, ethoxybutyl group, propoxybutyl group, Examples thereof include a methoxypentyl group, an ethoxypentyl group, a methoxyhexyl group, and a methoxyheptyl group.

  The optionally substituted alkyl group having 1 to 4 carbon atoms is not limited to the following, but examples thereof include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a tert group. -A butyl group is mentioned. Examples of the alkoxy group having 1 to 4 carbon atoms include, but are not limited to, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, and a tert-butoxy group. Examples of the phenyl group which may be substituted with an alkyl group having 1 to 4 carbon atoms, an alkoxy group, a nitro group, or an acetyl group include, but are not limited to, a phenyl group, a tolyl group, and a p-tert-butoxyphenyl group. , P-acetylphenyl group, and p-nitrophenyl group. Although not limited to the following as a C3-C5 heteroaromatic group, For example, a pyridyl group and a furyl group are mentioned.

  Specific examples of the acid generator include, but are not limited to, for example, tetramethylammonium trifluoromethanesulfonate, tetramethylammonium nonafluorobutanesulfonate, triethylammonium nonafluorobutanesulfonate, pyridinium nonafluorobutanesulfonate, camphor Triethylammonium sulfonate, pyridinium camphorsulfonate, tetra-n-butylammonium nonafluorobutanesulfonate, tetraphenylammonium nonafluorobutanesulfonate, tetramethylammonium p-toluenesulfonate, diphenyliodonium trifluoromethanesulfonate, trifluoromethanesulfonic acid (P-tert-butoxyphenyl) phenyliodonium, p-toluenesulfonic acid diphenyl P-toluenesulfonic acid (p-tert-butoxyphenyl) phenyliodonium, trifluoromethanesulfonic acid triphenylsulfonium, trifluoromethanesulfonic acid (p-tert-butoxyphenyl) diphenylsulfonium, trifluoromethanesulfonic acid bis (p-tert -Butoxyphenyl) phenylsulfonium, trifluoromethanesulfonic acid tris (p-tert-butoxyphenyl) sulfonium, p-toluenesulfonic acid triphenylsulfonium, p-toluenesulfonic acid (p-tert-butoxyphenyl) diphenylsulfonium, p-toluene Bis (p-tert-butoxyphenyl) phenylsulfonium sulfonate, tris (p-tert-butoxyv) p-toluenesulfonate Nyl) sulfonium, triphenylsulfonium nonafluorobutanesulfonate, triphenylsulfonium butanesulfonate, trimethylsulfonium trifluoromethanesulfonate, trimethylsulfonium p-toluenesulfonate, cyclohexylmethyl (2-oxocyclohexyl) sulfonium trifluoromethanesulfonate, p -Toluenesulfonate cyclohexylmethyl (2-oxocyclohexyl) sulfonium, trifluoromethanesulfonate dimethylphenylsulfonium, p-toluenesulfonate dimethylphenylsulfonium, trifluoromethanesulfonate dicyclohexylphenylsulfonium, p-toluenesulfonate dicyclohexylphenylsulfonium, trifluoromethane Trinaphthyl sulfonate Rufonium, cyclohexylmethyl trifluoromethanesulfonate (2-oxocyclohexyl) sulfonium, trifluoromethanesulfonate (2-norbornyl) methyl (2-oxocyclohexyl) sulfonium, ethylenebis [methyl (2-oxocyclopentyl) sulfonium trifluoromethanesulfonate] Onium salts such as 1,2′-naphthylcarbonylmethyltetrahydrothiophenium triflate; bis (benzenesulfonyl) diazomethane, bis (p-toluenesulfonyl) diazomethane, bis (xylenesulfonyl) diazomethane, bis (cyclohexylsulfonyl) diazomethane, Bis (cyclopentylsulfonyl) diazomethane, bis (n-butylsulfonyl) diazomethane, bis (isobutylsulfonyl) dia Zomethane, bis (sec-butylsulfonyl) diazomethane, bis (n-propylsulfonyl) diazomethane, bis (isopropylsulfonyl) diazomethane, bis (tert-butylsulfonyl) diazomethane, bis (n-amylsulfonyl) diazomethane, bis (isoamylsulfonyl) Diazomethane, bis (sec-amylsulfonyl) diazomethane, bis (tert-amylsulfonyl) diazomethane, 1-cyclohexylsulfonyl-1- (tert-butylsulfonyl) diazomethane, 1-cyclohexylsulfonyl-1- (tert-amylsulfonyl) diazomethane, Diazomethane derivatives such as 1-tert-amylsulfonyl-1- (tert-butylsulfonyl) diazomethane; bis- (p-toluenesulfonyl) -α- Methylglyoxime, bis- (p-toluenesulfonyl) -α-diphenylglyoxime, bis- (p-toluenesulfonyl) -α-dicyclohexylglyoxime, bis- (p-toluenesulfonyl) -2,3-pentanedione Oxime, bis- (p-toluenesulfonyl) -2-methyl-3,4-pentanedione glyoxime, bis- (n-butanesulfonyl) -α-dimethylglyoxime, bis- (n-butanesulfonyl) -α- Diphenylglyoxime, bis- (n-butanesulfonyl) -α-dicyclohexylglyoxime, bis- (n-butanesulfonyl) -2,3-pentanedione glyoxime, bis- (n-butanesulfonyl) -2-methyl- 3,4-pentanedione glyoxime, bis- (methanesulfonyl) -α-dimethyl Luglyoxime, bis- (trifluoromethanesulfonyl) -α-dimethylglyoxime, bis- (1,1,1-trifluoroethanesulfonyl) -α-dimethylglyoxime, bis- (tert-butanesulfonyl) -α-dimethyl Glyoxime, bis- (perfluorooctanesulfonyl) -α-dimethylglyoxime, bis- (cyclohexanesulfonyl) -α-dimethylglyoxime, bis- (benzenesulfonyl) -α-dimethylglyoxime, bis- (p-fluoro) Benzenesulfonyl) -α-dimethylglyoxime, bis- (p-tert-butylbenzenesulfonyl) -α-dimethylglyoxime, bis- (xylenesulfonyl) -α-dimethylglyoxime, bis- (camphorsulfonyl) -α- Dimethylglyoxime, etc. Oxime derivatives; bissulfone derivatives such as bisnaphthylsulfonylmethane, bistrifluoromethylsulfonylmethane, bismethylsulfonylmethane, bisethylsulfonylmethane, bispropylsulfonylmethane, bisisopropylsulfonylmethane, bis-p-toluenesulfonylmethane, bisbenzenesulfonylmethane Β-ketosulfone derivatives such as 2-cyclohexylcarbonyl-2- (p-toluenesulfonyl) propane and 2-isopropylcarbonyl-2- (p-toluenesulfonyl) propane; disulfone derivatives such as diphenyldisulfone derivatives and dicyclohexyldisulfone derivatives, p -Induction of nitrobenzyl sulfonates such as 2,6-dinitrobenzyl toluene sulfonate and 2,4-dinitrobenzyl p-toluene sulfonate Sulfonic acid such as 1,2,3-tris (methanesulfonyloxy) benzene, 1,2,3-tris (trifluoromethanesulfonyloxy) benzene, 1,2,3-tris (p-toluenesulfonyloxy) benzene Ester derivatives; N-hydroxysuccinimide methanesulfonate, N-hydroxysuccinimide trifluoromethanesulfonate, N-hydroxysuccinimide ethanesulfonate, N-hydroxysuccinimide 1-propanesulfonate, N-hydroxysuccinimide 2-propanesulfone Acid ester, N-hydroxysuccinimide 1-pentanesulfonic acid ester, N-hydroxysuccinimide 1-octanesulfonic acid ester, N-hydroxysuccinimide p-tolue Sulfonic acid ester, N-hydroxysuccinimide p-methoxybenzenesulfonic acid ester, N-hydroxysuccinimide 2-chloroethanesulfonic acid ester, N-hydroxysuccinimide benzenesulfonic acid ester, N-hydroxysuccinimide-2,4,6-trimethylbenzenesulfone Acid ester, N-hydroxysuccinimide 1-naphthalenesulfonic acid ester, N-hydroxysuccinimide 2-naphthalenesulfonic acid ester, N-hydroxy-2-phenylsuccinimide methanesulfonic acid ester, N-hydroxymaleimide methanesulfonic acid ester, N-hydroxy Maleimide ethane sulfonate, N-hydroxy-2-phenylmaleimide methanesulfonate, N-hydroxyglutar Imidomethanesulfonic acid ester, N-hydroxyglutarimide benzenesulfonic acid ester, N-hydroxyphthalimide methanesulfonic acid ester, N-hydroxyphthalimide benzenesulfonic acid ester, N-hydroxyphthalimide trifluoromethanesulfonic acid ester, N-hydroxyphthalimide p- Toluenesulfonic acid ester, N-hydroxynaphthalimide methanesulfonic acid ester, N-hydroxynaphthalimide benzenesulfonic acid ester, N-hydroxy-5-norbornene-2,3-dicarboximide methanesulfonic acid ester, N-hydroxy-5 -Norbornene-2,3-dicarboximide trifluoromethanesulfonic acid ester and N-hydroxy-5-norbornene-2,3-dicarboxyl Sulfonic acid ester derivatives of N- hydroxy imide compounds such as imide p- toluenesulfonic acid esters.

  Among these, in particular, triphenylsulfonium trifluoromethanesulfonate, trifluoromethanesulfonic acid (p-tert-butoxyphenyl) diphenylsulfonium, trifluoromethanesulfonic acid tris (p-tert-butoxyphenyl) sulfonium, p-toluenesulfonic acid Triphenylsulfonium, p-toluenesulfonic acid (p-tert-butoxyphenyl) diphenylsulfonium, p-toluenesulfonic acid tris (p-tert-butoxyphenyl) sulfonium, trifluoromethanesulfonic acid trinaphthylsulfonium, trifluoromethanesulfonic acid cyclohexylmethyl (2-oxocyclohexyl) sulfonium, trifluoromethanesulfonic acid (2-norbornyl) methyl (2-oxocyclohexyl) Sil) sulfonium, onium salts such as 1,2'-naphthylcarbonylmethyltetrahydrothiophenium triflate; bis (benzenesulfonyl) diazomethane, bis (p-toluenesulfonyl) diazomethane, bis (cyclohexylsulfonyl) diazomethane, bis (n- Diazomethane derivatives such as butylsulfonyl) diazomethane, bis (isobutylsulfonyl) diazomethane, bis (sec-butylsulfonyl) diazomethane, bis (n-propylsulfonyl) diazomethane, bis (isopropylsulfonyl) diazomethane, bis (tert-butylsulfonyl) diazomethane; Glyoxime derivatives such as bis- (p-toluenesulfonyl) -α-dimethylglyoxime and bis- (n-butanesulfonyl) -α-dimethylglyoxime; Bissulfone derivatives such as naphthylsulfonylmethane; N-hydroxysuccinimide methanesulfonate, N-hydroxysuccinimide trifluoromethanesulfonate, N-hydroxysuccinimide 1-propanesulfonate, N-hydroxysuccinimide 2-propanesulfonate, N-hydroxysuccinimide 1-pentanesulfonic acid ester, N-hydroxysuccinimide p-toluenesulfonic acid ester, N-hydroxynaphthalimide methanesulfonic acid ester, and N-hydroxynaphthalimide benzenesulfonic acid ester, etc. A sulfonic acid ester derivative is preferably used.

  In the composition for forming a lower layer film for lithography of the present embodiment, the content of the acid generator is not particularly limited, but is 0.0 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the cyanate ester compound. Preferably, it is 0.0 mass part or more and 40 mass parts or less. By setting it as the above preferable range, the crosslinking reaction tends to be enhanced, and the occurrence of the mixing phenomenon with the resist layer tends to be suppressed.

  The composition for forming a lower layer film for lithography of the present embodiment may further contain a basic compound from the viewpoint of improving storage stability.

  The basic compound serves as a quencher for the acid to prevent the acid generated in a trace amount from the acid generator from causing the crosslinking reaction to proceed. Examples of such basic compounds include primary, secondary or tertiary aliphatic amines, hybrid amines, aromatic amines, heterocyclic amines, nitrogen-containing compounds having a carboxy group, A nitrogen-containing compound having a sulfonyl group, a nitrogen-containing compound having a hydroxyl group, a nitrogen-containing compound having a hydroxyphenyl group, an alcoholic nitrogen-containing compound, an amide derivative, and an imide derivative are exemplified, but not limited thereto.

  Specific examples of the primary aliphatic amines include, but are not limited to, ammonia, methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, sec-butylamine, tert- Examples include butylamine, pentylamine, tert-amylamine, cyclopentylamine, hexylamine, cyclohexylamine, heptylamine, octylamine, nonylamine, decylamine, dodecylamine, cetylamine, methylenediamine, ethylenediamine, and tetraethylenepentamine. Specific examples of secondary aliphatic amines include, but are not limited to, dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, diisobutylamine, di-sec- Butylamine, dipentylamine, dicyclopentylamine, dihexylamine, dicyclohexylamine, diheptylamine, dioctylamine, dinonylamine, didecylamine, didodecylamine, dicetylamine, N, N-dimethylmethylenediamine, N, N-dimethylethylenediamine, and N, N-dimethyltetraethylenepentamine is mentioned. Specific examples of tertiary aliphatic amines include, but are not limited to, for example, trimethylamine, triethylamine, tri-n-propylamine, triisopropylamine, tri-n-butylamine, triisobutylamine, tri-sec. -Butylamine, tripentylamine, tricyclopentylamine, trihexylamine, tricyclohexylamine, triheptylamine, trioctylamine, trinonylamine, tridecylamine, tridodecylamine, tricetylamine, N, N, N ', Examples include N′-tetramethylmethylenediamine, N, N, N ′, N′-tetramethylethylenediamine, and N, N, N ′, N′-tetramethyltetraethylenepentamine.

  Specific examples of hybrid amines include, but are not limited to, dimethylethylamine, methylethylpropylamine, benzylamine, phenethylamine, and benzyldimethylamine. Specific examples of aromatic amines and heterocyclic amines include, but are not limited to, for example, aniline derivatives (for example, aniline, N-methylaniline, N-ethylaniline, N-propylaniline, N, N-dimethylaniline). 2-methylaniline, 3-methylaniline, 4-methylaniline, ethylaniline, propylaniline, trimethylaniline, 2-nitroaniline, 3-nitroaniline, 4-nitroaniline, 2,4-dinitroaniline, 2,6 -Dinitroaniline, 3,5-dinitroaniline, N, N-dimethyltoluidine, etc.), diphenyl (p-tolyl) amine, methyldiphenylamine, triphenylamine, phenylenediamine, naphthylamine, diaminonaphthalene, pyrrole derivatives (eg pyrrole, 2H -Pyrrole, 1 Methylpyrrole, 2,4-dimethylpyrrole, 2,5-dimethylpyrrole, N-methylpyrrole, etc.), oxazole derivatives (eg oxazole, isoxazole etc.), thiazole derivatives (eg thiazole, isothiazole etc.), imidazole derivatives (eg Imidazole, 4-methylimidazole, 4-methyl-2-phenylimidazole, etc.), pyrazole derivatives, furazane derivatives, pyrroline derivatives (eg pyrroline, 2-methyl-1-pyrroline etc.), pyrrolidine derivatives (eg pyrrolidine, N-methylpyrrolidine etc.) Pyrrolidinone, N-methylpyrrolidone, etc.), imidazoline derivatives, imidazolidine derivatives, pyridine derivatives (for example, pyridine, methylpyridine, ethylpyridine, propylpyridine, butylpyridine, 4- (1-butyrate) Pentyl) pyridine, dimethylpyridine, trimethylpyridine, triethylpyridine, phenylpyridine, 3-methyl-2-phenylpyridine, 4-tert-butylpyridine, diphenylpyridine, benzylpyridine, methoxypyridine, butoxypyridine, dimethoxypyridine, 1-methyl 2-pyridone, 4-pyrrolidinopyridine, 1-methyl-4-phenylpyridine, 2- (1-ethylpropyl) pyridine, aminopyridine, dimethylaminopyridine, etc.), pyridazine derivatives, pyrimidine derivatives, pyrazine derivatives, pyrazoline derivatives , Pyrazolidine derivatives, piperidine derivatives, piperazine derivatives, morpholine derivatives, indole derivatives, isoindole derivatives, 1H-indazole derivatives, indoline derivatives, quinoline derivatives (eg Quinoline, 3-quinolinecarbonitrile, etc.), isoquinoline derivatives, cinnoline derivatives, quinazoline derivatives, quinoxaline derivatives, phthalazine derivatives, purine derivatives, pteridine derivatives, carbazole derivatives, phenanthridine derivatives, acridine derivatives, phenazine derivatives, 1,10- Examples include phenanthroline derivatives, adenine derivatives, adenosine derivatives, guanine derivatives, guanosine derivatives, uracil derivatives, and uridine derivatives.

  Further, specific examples of the nitrogen-containing compound having a carboxy group include, but are not limited to, for example, aminobenzoic acid, indolecarboxylic acid, and amino acid derivatives (for example, nicotinic acid, alanine, arginine, aspartic acid, glutamic acid, glycine, Histidine, isoleucine, glycylleucine, leucine, methionine, phenylalanine, threonine, lysine, 3-aminopyrazine-2-carboxylic acid, methoxyalanine). Specific examples of the nitrogen-containing compound having a sulfonyl group include, but are not limited to, 3-pyridinesulfonic acid and pyridinium p-toluenesulfonate. Specific examples of the nitrogen-containing compound having a hydroxyl group, the nitrogen-containing compound having a hydroxyphenyl group, and the alcoholic nitrogen-containing compound are not limited to the following. For example, 2-hydroxypyridine, aminocresol, 2,4-quinolinediol 3-indolemethanol hydrate, monoethanolamine, diethanolamine, triethanolamine, N-ethyldiethanolamine, N, N-diethylethanolamine, triisopropanolamine, 2,2′-iminodiethanol, 2-aminoethanol, 3 -Amino-1-propanol, 4-amino-1-butanol, 4- (2-hydroxyethyl) morpholine, 2- (2-hydroxyethyl) pyridine, 1- (2-hydroxyethyl) piperazine, 1- [2- (2-hydroxyethoxy ) Ethyl] piperazine, piperidineethanol, 1- (2-hydroxyethyl) pyrrolidine, 1- (2-hydroxyethyl) -2-pyrrolidinone, 3-piperidino-1,2-propanediol, 3-pyrrolidino-1,2- Propanediol, 8-hydroxyurolidine, 3-quinuclidinol, 3-tropanol, 1-methyl-2-pyrrolidine ethanol, 1-aziridine ethanol, N- (2-hydroxyethyl) phthalimide, and N- (2- Hydroxyethyl) isonicotinamide. Specific examples of the amide derivative include, but are not limited to, for example, formamide, N-methylformamide, N, N-dimethylformamide, acetamide, N-methylacetamide, N, N-dimethylacetamide, propionamide, and benzamide. Can be mentioned. Specific examples of the imide derivative include, but are not limited to, phthalimide, succinimide, and maleimide.

  In the composition for forming a lower layer film for lithography of the present embodiment, the content of the basic compound is not particularly limited, but is 0.0 parts by mass or more and 2.0 parts by mass or less with respect to 100 parts by mass of the cyanate ester compound. It is preferable that it is 0.0 mass part or more and 1.0 mass part or less more preferably. By making it into the above preferred range, the storage stability tends to be enhanced without excessively impairing the crosslinking reaction.

  In addition, the composition for forming a lower layer film for lithography of the present embodiment may contain other resins and / or compounds for the purpose of imparting thermosetting properties and controlling absorbance. Examples of such other resins and / or compounds include naphthol resins, xylene resins, naphthol-modified resins, phenol-modified resins of naphthalene resins, polyhydroxystyrene, dicyclopentadiene resins, (meth) acrylates, dimethacrylates, trimethacrylates, tetra Naphthalene rings such as methacrylate, vinylnaphthalene and polyacenaphthylene; biphenyl rings such as phenanthrenequinone and fluorene; resins containing heterocycles having heteroatoms such as thiophene and indene; resins not containing aromatic rings; rosin resins; Resins and compounds having an alicyclic structure such as cyclodextrin, adamantane (poly) ol, tricyclodecane (poly) ol, and derivatives thereof are exemplified, but not limited thereto. Furthermore, the composition for forming a lower layer film for lithography of the present embodiment may contain a known additive. Known additives include, but are not limited to, ultraviolet absorbers, surfactants, colorants, and nonionic surfactants.

[Liquid lower layer film and pattern forming method]
The underlayer film for lithography of the present embodiment is formed using the composition for forming an underlayer film for lithography of the present embodiment.

  Further, the resist pattern forming method of the present embodiment includes a step (A-1) of forming a lower layer film on the substrate using the composition for forming a lower layer film for lithography of the present embodiment, and on the lower layer film, A step (A-2) of forming at least one photoresist layer; and a step (A-3) of irradiating a predetermined region of the photoresist layer with radiation and developing.

  Furthermore, the circuit pattern forming method of the present embodiment includes a step (B-1) of forming a lower layer film on the substrate using the composition for forming a lower layer film for lithography of the present embodiment, on the lower layer film, A step of forming an intermediate layer film using a resist intermediate layer film material containing silicon atoms (B-2), and a step of forming at least one photoresist layer on the intermediate layer film (B-3) Irradiating a predetermined region of the photoresist layer with radiation to form a developed resist pattern (B-4); etching the intermediate layer film using the resist pattern as a mask; A step (B-5) of forming, a step (B-6) of forming the lower layer film pattern by etching the lower layer film using the intermediate layer film pattern as an etching mask, and etching the lower layer film pattern The substrate is etched as a mask, has a step of forming a substrate pattern (B-7), the.

  If the lower layer film for lithography of this embodiment is formed from the composition for lower layer film formation for lithography of this embodiment, the formation method will not be specifically limited, A well-known method is applicable. For example, by applying the composition for forming a lower layer film for lithography of the present embodiment on a substrate by a known coating method such as spin coating or screen printing or a printing method, the organic solvent is volatilized and removed. A lower layer film can be formed.

  At the time of forming the lower layer film, baking is preferably performed in order to suppress the occurrence of the mixing phenomenon with the upper layer resist and to promote the crosslinking reaction. In this case, the baking temperature is not particularly limited, but is preferably in the range of 80 to 450 ° C, more preferably 200 to 400 ° C. Further, the baking time is not particularly limited, but is preferably in the range of 10 to 300 seconds. The thickness of the lower layer film can be appropriately selected according to the required performance, and is not particularly limited, but is preferably 30 nm or more and 20000 nm or less, and more preferably 50 nm or more and 15000 nm or less.

  After forming the lower layer film on the substrate, in the case of a two-layer process, a silicon-containing resist layer thereon, or a single-layer resist made of ordinary hydrocarbon, in the case of a three-layer process, a silicon-containing intermediate layer thereon, It is preferable to form a single layer resist layer not containing silicon thereon. In this case, a well-known thing can be used as a photoresist material for forming this resist layer.

  As a silicon-containing resist material for a two-layer process, from the viewpoint of oxygen gas etching resistance, a silicon atom-containing polymer such as a polysilsesquioxane derivative or a vinylsilane derivative is used as a base polymer, and an organic solvent, an acid generator, If necessary, a positive photoresist material containing a basic compound or the like is preferably used. Here, as the silicon atom-containing polymer, a known polymer used in this type of resist material can be used.

  A polysilsesquioxane-based intermediate layer is preferably used as the silicon-containing intermediate layer for the three-layer process. By giving the intermediate layer an effect as an antireflection film, reflection tends to be effectively suppressed. For example, in a 193 nm exposure process, if a material containing many aromatic groups and high substrate etching resistance is used as the lower layer film, the k value increases and the substrate reflection tends to increase, but the reflection is suppressed in the intermediate layer. Thus, the substrate reflection can be reduced to 0.5% or less. The intermediate layer having such an antireflection effect is not limited to the following, but for 193 nm exposure, a polysilsesquioxy crosslinked with an acid or heat into which a light absorbing group having a phenyl group or a silicon-silicon bond is introduced. Sun is preferably used.

  In addition, an intermediate layer formed by a chemical vapor deposition (CVD) method can also be used. The intermediate layer having a high effect as an antireflection film produced by the CVD method is not limited to the following, but for example, a SiON film is known. In general, the formation of the intermediate layer by a wet process such as spin coating or screen printing has a simpler and more cost-effective advantage than the CVD method. The upper layer resist in the three-layer process may be either a positive type or a negative type, and the same one as a commonly used single layer resist can be used.

  Furthermore, the lower layer film of this embodiment can also be used as an antireflection film for a normal single layer resist or a base material for suppressing pattern collapse. Since the lower layer film of this embodiment is excellent in etching resistance for the base processing, it can be expected to function as a hard mask for the base processing.

  When the resist layer is formed from the photoresist material, a wet process such as spin coating or screen printing is preferably used as in the case of forming the lower layer film. Further, after the resist material is applied by spin coating or the like, prebaking is usually performed, but this prebaking is preferably performed at 80 to 180 ° C. for 10 to 300 seconds. Then, according to a conventional method, a resist pattern can be obtained by performing exposure, post-exposure baking (PEB), and development. The thickness of the resist film is not particularly limited, but is preferably 30 nm or more and 500 nm or less, and more preferably 50 nm or more and 400 nm or less.

  The exposure light may be appropriately selected and used depending on the photoresist material to be used. Examples of the exposure light include high energy rays having a wavelength of 300 nm or less, specifically, 248 nm, 193 nm, 157 nm excimer laser, 3-20 nm soft X-ray, electron beam, and X-ray.

  The resist pattern formed by the above method is one in which pattern collapse is suppressed by the lower layer film of the present embodiment. Therefore, by using the lower layer film of this embodiment, a finer pattern can be obtained, and the exposure amount necessary for obtaining the resist pattern can be reduced.

Next, etching is performed using the obtained resist pattern as a mask. Gas etching is preferably used as the etching of the lower layer film in the two-layer process. As gas etching, etching using oxygen gas is suitable. In addition to oxygen gas, He, and an inert gas such as _{Ar, CO,} it is also possible to add _{CO 2, NH 3, SO 2} , N 2, NO 2, H 2 gas. Further, gas etching can be performed using only CO, CO ₂ , NH ₃ , N ₂ , NO ₂ , and H ₂ gas without using oxygen gas. In particular, the latter gas is preferably used for side wall protection for preventing undercut of the pattern side wall.

  On the other hand, gas etching is also preferably used in the etching of the intermediate layer in the three-layer process. As the gas etching, the same one as described in the above two-layer process can be applied. In particular, the processing of the intermediate layer in the three-layer process is preferably performed using a fluorocarbon gas and a resist pattern as a mask. Thereafter, as described above, the lower layer film can be processed by, for example, oxygen gas etching using the intermediate layer pattern as a mask.

  Here, when an inorganic hard mask intermediate layer film is formed as an intermediate layer, a silicon oxide film, a silicon nitride film, or a silicon oxynitride film (SiON film) is formed by CVD or ALD. The method for forming the nitride film is not limited to the following, but for example, a method described in Japanese Patent Application Laid-Open No. 2002-334869 (Patent Document 6) and WO 2004/066377 (Patent Document 7) can be used. A photoresist film can be formed directly on such an intermediate film, but an organic antireflection film (BARC) is formed on the intermediate film by spin coating, and a photoresist film is formed thereon. May be.

  As the intermediate layer, a polysilsesquioxane-based intermediate layer is also preferably used. By providing the resist intermediate layer film with an effect as an antireflection film, reflection tends to be effectively suppressed. Specific materials of the polysilsesquioxane-based intermediate layer are not limited to the following, but are described, for example, in JP-A-2007-226170 (Patent Document 8) and JP-A-2007-226204 (Patent Document 9). Can be used.

Etching of the next substrate can also be performed by a conventional method. For example, if the substrate is SiO ₂ or SiN, etching mainly using a chlorofluorocarbon gas, if p-Si, Al, or W is chlorine or bromine, Etching mainly with gas can be performed. When the substrate is etched with a chlorofluorocarbon gas, the silicon-containing resist of the two-layer resist process and the silicon-containing intermediate layer of the three-layer process are peeled off simultaneously with the substrate processing. On the other hand, when the substrate is etched with a chlorine-based or bromine-based gas, the silicon-containing resist layer or the silicon-containing intermediate layer is separately peeled, and generally, dry etching peeling with a chlorofluorocarbon-based gas is performed after the substrate processing. .

The lower layer film of this embodiment is excellent in the etching resistance of these substrates. A known substrate can be appropriately selected and used, and is not particularly limited. Examples thereof include Si, α-Si, p-Si, SiO ₂ , SiN, SiON, W, TiN, and Al. . The substrate may be a laminate having a film to be processed (substrate to be processed) on a base material (support). Examples of such a film to be processed include various low-k films of Si, SiO ₂ , SiON, SiN, p-Si, α-Si, W, W-Si, Al, Cu, and Al—Si, and the like. Examples thereof include a stopper film, and a material different from that of the substrate (support) is preferably used. The thickness of the substrate or film to be processed is not particularly limited, but is preferably 50 nm or more and 10,000 nm or less, and more preferably 75 to 5,000 nm.

  Hereinafter, the present embodiment will be described in more detail with reference to synthesis examples, examples, and comparative examples, but the present embodiment is not limited to these examples.

[Carbon concentration and oxygen concentration]
The carbon concentration and oxygen concentration (mass%) were measured by organic elemental analysis using the following apparatus.
Apparatus: CHN coder MT-6 (trade name, manufactured by Yanaco Analytical Co., Ltd.)

[Weight average molecular weight]
The weight average molecular weight (Mw) in terms of polystyrene was determined by gel permeation chromatography (GPC) analysis using the following apparatus and the like.
Apparatus: Shodex GPC-101 type (trade name, manufactured by Showa Denko KK)
Column: KF-80M x 3
Eluent: THF 1mL / min
Temperature: 40 ° C

[solubility]
At 23 ° C., the amount of the compound dissolved in propylene glycol monomethyl ether acetate (PGMEA) was measured, and the solubility was evaluated based on the results based on the following criteria.
Evaluation A: 20% by mass or more Evaluation B: Less than 20% by mass

<Synthesis Example 1> Synthesis of cyanate ester compound of naphthol-modified naphthalene formaldehyde resin (hereinafter also abbreviated as “NMCNCN”) (synthesis of naphthalene formaldehyde resin)
Stirring 1277g of 37 mass% formalin aqueous solution (15.8mol as formaldehyde, manufactured by Mitsubishi Gas Chemical Co., Ltd.) and 634g of 98 mass% sulfuric acid (manufactured by Mitsubishi Gas Chemical Co., Ltd.) under reflux at around 100 ° C under normal pressure. Then, 553 g (3.5 mol, manufactured by Mitsubishi Gas Chemical Co., Ltd.) of 1-naphthalenemethanol melted here was added dropwise over 4 hours, and then further reacted for 2 hours. To the obtained reaction solution, 500 g of ethylbenzene (manufactured by Wako Pure Chemical Industries, Ltd.) and 500 g of methyl isobutyl ketone (manufactured by Wako Pure Chemical Industries, Ltd.) are added as diluent solvents, and after standing, the lower aqueous phase is added. Removed. Further, the reaction solution was neutralized and washed with water, and ethylbenzene and methyl isobutyl ketone were distilled off under reduced pressure to obtain 624 g of a pale yellow solid naphthalene formaldehyde resin.

(Synthesis of naphthol-modified naphthalene formaldehyde resin)
After the above-obtained naphthalene formaldehyde resin 500 g (containing oxygen 3.9 mol) and naphthol 1395 g (9.7 mol, manufactured by Sugai Chemical Industry Co., Ltd.) were heated and melted at 100 ° C., paratoluene sulfone was stirred. 200 mg of acid (manufactured by Wako Pure Chemical Industries, Ltd.) was added to initiate the reaction. The reaction was allowed to proceed for 2.5 hours while raising the temperature to 170 ° C. Thereafter, the obtained reaction solution was diluted with 2500 g of a mixed solvent (meta-xylene (manufactured by Mitsubishi Gas Chemical Co., Inc.) / Methyl isobutyl ketone (manufactured by Wako Pure Chemical Industries, Ltd.) = 1/1 (mass ratio)). Thereafter, neutralization and washing with water were performed, and the solvent and unreacted raw materials were removed under reduced pressure to obtain 1125 g of a black-brown solid naphthol-modified naphthalene formaldehyde resin represented by the following formula (11). The obtained naphthol-modified naphthalene formaldehyde resin had an OH value of 232 mg KOH / g (OH group equivalent was 241 g / eq.).

式（１１）中、Ｒ_１、ｍ、及びｎは、上述した式（１）で説明したものと同義である。

In formula (11), R ₁ , m, and n are synonymous with those described in formula (1) above.

(Synthesis of NMCN)
730 g of naphthol-modified naphthalene formaldehyde resin represented by the formula (11) obtained by the above method (OH group equivalent: 241 g / eq.) (OH group conversion: 3.03 mol) (weight average molecular weight Mw 390) and triethylamine 459.8 g (4 .54 mol) (1.5 mol with respect to 1 mol of hydroxy group) was dissolved in 4041 g of dichloromethane to obtain Solution 1. 298.4 g (4.85 mol) of cyanogen chloride (1.6 mol with respect to 1 mol of hydroxy group), 661.6 g of dichloromethane, 460.2 g (4.54 mol) of 36% hydrochloric acid (1. 5 mol) and 2853.2 g of water were poured over 72 minutes while stirring at a liquid temperature of −2 to −0.5 ° C. After the pouring of solution 1 was completed, the mixture was stirred at the same temperature for 30 minutes, and then a solution (solution 2) in which 183.9 g (1.82 mol) of triethylamine (0.6 mol with respect to 1 mol of hydroxy group) was dissolved in 184 g of dichloromethane. ) Was poured over 25 minutes. After the end of pouring the solution 2, the reaction was completed by stirring at the same temperature for 30 minutes.

  Thereafter, the reaction solution was allowed to stand to separate the organic phase and the aqueous phase. The obtained organic phase was washed 5 times with 2000 g of water. The electric conductivity of the waste water in the fifth washing with water was 20 μS / cm, and it was confirmed that the ionic compounds that could be removed were sufficiently removed by washing with water.

The organic phase after washing with water was concentrated under reduced pressure and finally concentrated to dryness at 90 ° C. for 1 hour to obtain 797 g of a cyanate ester compound (brown viscous material) represented by the following formula (1-2). (A typical composition as the cyanate ester compound is a compound represented by the following formula (10)). The obtained cyanate ester compound (NMCNCN) had a weight average molecular weight Mw of 490. Further, the IR spectrum of NMCN showed an absorption of 2260 cm ⁻¹ (cyanate ester group) and no absorption of a hydroxy group. As a result of thermogravimetry (TG), the 20% heat loss temperature of the obtained cyanate ester compound (NMCNN) was 400 ° C. or higher. Therefore, it was evaluated that it has high heat resistance and can be applied to high temperature baking. As a result of evaluating the solubility in PGMEA, it was 20% by mass or more (Evaluation A), and the cyanate ester compound (NMCNCN) was evaluated as having excellent solubility. Therefore, it is evaluated that the cyanate ester compound (NMCNN) has high storage stability in a solution state and can be sufficiently applied to an edge beat rinse liquid (PGME / PGMEA mixed liquid) widely used in a semiconductor microfabrication process. It was done.

式（１−２）中、Ｒ_１、ｍ、及びｎは、上述した式（１）で説明したものと同義である。

In formula (1-2), R ₁ , m, and n have the same meaning as described in formula (1) above.

<Production Example 1> Production of modified resin (hereinafter also abbreviated as “CR-1”) A four-necked flask having an internal volume of 10 L and equipped with a Dimroth condenser, thermometer and stirring blade is prepared. did. To this four-necked flask, in a nitrogen stream, 1.09 kg of 1,5-dimethylnaphthalene (7 mol, manufactured by Mitsubishi Gas Chemical Co., Ltd.), 2.1 kg of 40% by weight formalin aqueous solution (28 mol of formaldehyde, Mitsubishi Gas Chemical Co., Ltd.) )) And 98 mass% sulfuric acid (manufactured by Kanto Chemical Co., Ltd.) 0.97 ml were charged and reacted for 7 hours under reflux at 100 ° C. under normal pressure. Thereafter, 1.8 kg of ethylbenzene (special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.) as a diluent solvent was added to the reaction solution, and after standing, the lower aqueous phase was removed. Further, neutralization and washing with water were performed, and ethylbenzene and unreacted 1,5-dimethylnaphthalene were distilled off under reduced pressure to obtain 1.25 kg of a light brown solid dimethylnaphthalene formaldehyde resin. The molecular weight of the obtained dimethylnaphthalene formaldehyde was Mn: 562, Mw: 1168, Mw / Mn: 2.08. Moreover, carbon concentration was 84.2 mass% and oxygen concentration was 8.3 mass%.

  Subsequently, a four-necked flask having an internal volume of 0.5 L equipped with a Dimroth condenser, a thermometer, and a stirring blade was prepared. This four-necked flask was charged with 100 g (0.51 mol) of the dimethylnaphthalene formaldehyde resin obtained as described above and 0.05 g of paratoluenesulfonic acid under a nitrogen stream and heated to 190 ° C. Stir after heating for hours. Thereafter, 52.0 g (0.36 mol) of 1-naphthol was further added, and the temperature was further raised to 220 ° C. to react for 2 hours. After the solvent was diluted, neutralization and water washing were performed, and the solvent was removed under reduced pressure to obtain 126.1 g of a dark brown solid modified resin (CR-1). The obtained modified resin (CR-1) was Mn: 885, Mw: 2220, Mw / Mn: 4.17. The carbon concentration was 89.1% by mass, and the oxygen concentration was 4.5% by mass. As a result of evaluating the solubility in PGMEA, it was 20% by mass or more (Evaluation A), and was evaluated as having excellent solubility.

<Examples 1-2 and Comparative Examples 1-2>
Using the cyanate ester compound (NMCNN) obtained in Synthesis Example 1 above, the modified resin (PGMEA) obtained in Production Example 1 and the following materials so as to have the composition shown in Table 1, Examples The lower layer film forming materials for lithography corresponding to 1-2 and Comparative Examples 1-2 were prepared.
Acid generator: Ditertiary butyl diphenyliodonium nonafluoromethanesulfonate (DTDPI) manufactured by Midori Chemical Co., Ltd.
Cross-linking agent: Nikalac MX270 (Nikalac) manufactured by Sanwa Chemical Co., Ltd.
Organic solvent: Propylene glycol monomethyl ether acetate (PGMEA)

  Next, each composition for lower layer film formation of Examples 1-2 and Comparative Examples 1-2 is spin-coated on a silicon substrate, and then baked at 180 ° C. for 60 seconds and further at 400 ° C. for 120 seconds to form a film. Each 200 nm-thick lower layer film was produced. The following [Etching Resistance] and [Heat Resistance] were evaluated under the conditions of [Etching Test] shown below.

[Etching test]
Etching device: RIE-10NR manufactured by Samco International
Output: 50W
Pressure: 4Pa
Time: 2min
Etching gas CF ₄ gas flow rate: O ₂ gas flow rate = 5: 15 (sccm)

[Etching resistance]
The etching resistance was evaluated by the following procedure. First, a novolak underlayer film was formed under the same conditions as in Example 1 except that novolak (PSM4357 manufactured by Gunei Chemical Co., Ltd.) was used in place of the compound (NMCNCN) in Example 1 and the drying temperature was 110 ° C. Produced. Then, the above-described etching test was performed on this novolac lower layer film, and the etching rate at that time was measured.

Next, the above-mentioned etching test was similarly performed for the lower layer films of Examples 1-2 and Comparative Examples 1-2, and the etching rate at that time was measured. Then, the etching resistance was evaluated according to the following evaluation criteria based on the etching rate of the novolak underlayer film. From a practical viewpoint, the following evaluation A or evaluation B is preferable.
<Evaluation criteria>
Evaluation A: Etching rate is less than −20% compared to the etching rate of the novolac lower layer film Evaluation B: Etching rate is −20% to −10% compared to the etching rate of the novolak lower layer film Evaluation C: Novolak Etching rate is -10% or more and 0% or less compared to the etching rate of the lower layer film

[Heat-resistant]
Product name manufactured by SII Nanotechnology: EXSTAR6000TG-DTA apparatus, about 5 mg of sample is put in an aluminum non-sealed container, and the temperature is raised at a rate of 10 ° C./min in a nitrogen gas (300 mL / min) stream at 500 ° C. The amount of decrease in thermogravimetry was measured by raising the temperature up to. From a practical viewpoint, the following evaluation A or evaluation B is preferable.
<Evaluation criteria>
Evaluation A: Thermal weight reduction at 400 ° C. is less than 20% Evaluation B: Thermal weight reduction at 400 ° C. is 20% or more and 30% or less Evaluation C: Thermal weight reduction at 400 ° C. is 30% Super

<Example 3>
The composition for forming a lower layer film for lithography in Example 1 was applied onto a 300 nm thick SiO ₂ substrate and baked at 240 ° C. for 60 seconds and further at 400 ° C. for 120 seconds, thereby forming a lower layer film having a thickness of 70 nm. Formed. On this lower layer film, an ArF resist solution was applied and baked at 130 ° C. for 60 seconds to form a 140 nm-thick photoresist layer. The resist solution for ArF is prepared by blending a compound of the following formula (12): 5 parts by mass, triphenylsulfonium nonafluoromethanesulfonate: 1 part by mass, tributylamine: 2 parts by mass, and PGMEA: 92 parts by mass. What was done was used.

  In addition, the compound of following formula (12) was prepared as follows. That is, 4.15 g of 2-methyl-2-methacryloyloxyadamantane, 3.00 g of methacryloyloxy-γ-butyrolactone, 2.08 g of 3-hydroxy-1-adamantyl methacrylate, 0.38 g of azobisisobutyronitrile, The reaction solution was dissolved in 80 mL. This reaction solution was polymerized for 22 hours while maintaining the reaction temperature at 63 ° C. in a nitrogen atmosphere, and then the reaction solution was dropped into 400 mL of n-hexane. The product resin thus obtained was coagulated and purified, and the resulting white powder was filtered and dried overnight at 40 ° C. under reduced pressure to obtain a compound represented by the following formula.

式（１２）中、４０、４０、２０とあるのは、各構成単位の比率を示すものであり、ブロック共重合体を示すものではない。

In the formula (12), 40, 40, and 20 indicate the ratio of each structural unit, and do not indicate a block copolymer.

  Subsequently, the photoresist layer was exposed using an electron beam drawing apparatus (manufactured by Elionix; ELS-7500, 50 keV), baked (PEB) at 115 ° C. for 90 seconds, and 2.38 mass% tetramethylammonium hydroxide ( A positive resist pattern was obtained by developing with an aqueous solution of TMAH for 60 seconds. The evaluation results are shown in Table 2.

<Example 4>
A positive resist pattern was obtained in the same manner as in Example 3, except that the composition for forming an underlayer film for lithography in Example 2 was used instead of the composition for forming an underlayer film for lithography in Example 1 above. . The evaluation results are shown in Table 2.

<Comparative Example 3>
A photoresist layer was directly formed on the SiO 2 substrate in the same manner as in Example 3 except that the lower layer film was not formed to obtain a positive resist pattern. The evaluation results are shown in Table 2.

[Evaluation]
About each of the said Example 3, 4 and the comparative example 3, the shape of the obtained resist pattern of 55 nmL / S (1: 1) and 80 nmL / S (1: 1) was made into the electron microscope made from Hitachi, Ltd. (S -4800). As for the shape of the resist pattern after development, the resist pattern was not collapsed and the rectangular shape was good, and the resist pattern was evaluated as bad. As a result of the observation, the minimum line width with no pattern collapse and good rectangularity was used as an evaluation index as the resolution. Furthermore, the minimum amount of electron beam energy that can draw a good pattern shape is used as an evaluation index as sensitivity.

  As is clear from Table 2, Examples 3 and 4 using the composition for forming an underlayer film containing a cyanate ester compound have a resolution higher than that of Comparative Example 3 using no composition for forming an underlayer film. It was at least confirmed that both sexiness and sensitivity were significantly superior. In addition, it was confirmed at least that the resist pattern shape after development had no pattern collapse and had good rectangularity. Furthermore, from the difference in resist pattern shape after development, it was at least confirmed that the lower layer film obtained from the composition for lower layer film for lithography of Examples 3 and 4 had good adhesion to the resist material.

  This application is based on a Japanese patent application (Japanese Patent Application No. 2015-041370) filed with the Japan Patent Office on March 3, 2015, the contents of which are incorporated herein by reference.

  The material for forming a lower layer film for lithography according to the present invention has relatively high heat resistance, relatively high solvent solubility, excellent embedding characteristics in a stepped substrate, etc., and flatness of the film, and a wet process can be applied. It is. Therefore, the material for forming an underlayer film for lithography according to the present invention, the composition containing the material, and the underlayer film formed using the composition can be widely and effectively used in various applications that require the above performance. It is.

Claims (13)

  A material for forming an underlayer film for lithography, comprising a cyanate ester compound obtained by cyanating a modified naphthalene formaldehyde resin. The material for forming an underlayer film for lithography according to claim 1, wherein the cyanate ester compound is a compound represented by the following formula (1).

(In formula (1), each Ar ₁ independently represents an aromatic ring structure, and each R ₁ independently represents a methylene group, a methyleneoxy group, a methyleneoxymethylene group, or an oxymethylene group, or a combination thereof. R ₂ represents each independently a monovalent substituent hydrogen atom, alkyl group or aryl group, and R ₃ each independently represents an alkyl group or aryl group having 1 to 3 carbon atoms. , Hydroxy group, or hydroxymethylene group, m represents an integer of 1 or more, n represents an integer of 0 or more, and the arrangement of each repeating unit is arbitrary, k is the number of bonds of the cyanate group. An integer of 1 to 3 is shown, x is an integer of “the number of bonds of Ar ₁ − (k + 2)” which is the number of bonds of R ₂ , and y is an integer of 0 to 4.   The underlayer film formation for lithography according to claim 1 or 2, wherein the modified naphthalene formaldehyde resin is a resin obtained by modifying a naphthalene formaldehyde resin or a deacetal-bound naphthalene formaldehyde resin with a hydroxy-substituted aromatic compound. Materials.   The hydroxy-substituted aromatic compound is one or more selected from the group consisting of phenol, 2,6-xylenol, naphthol, dihydroxynaphthalene, biphenol, hydroxyanthracene, and dihydroxyanthracene. Material for forming a lower layer film for lithography.   The material for forming a lower layer film for lithography according to any one of claims 1 to 4, wherein the cyanate ester compound has a weight average molecular weight of 200 or more and 25000 or less. The material for forming an underlayer film for lithography according to any one of claims 2 to 5, wherein the compound represented by the formula (1) is a compound represented by the following formula (1-1).

(In Formula (1-1), R _{1 to} R ₃ , k, m, n, and y are as defined in Formula (1) above, and x represents an integer of (6-k). .) The material for forming an underlayer film for lithography according to claim 6, wherein the compound represented by the formula (1-1) is a compound represented by the following formula (1-2).

(In formula (1-2), R ₁ , m and n have the same meanings as described in formula (1).)   The composition for lower-layer film formation for lithography containing the material for lower-layer film formation for lithography as described in any one of Claims 1-7, and a solvent.   The composition for forming a lower layer film for lithography according to claim 8, further comprising an acid generator.   The composition for forming a lower layer film for lithography according to claim 8 or 9, further comprising a crosslinking agent.   An underlayer film for lithography formed using the composition for forming an underlayer film for lithography according to any one of claims 8 to 10. Forming a lower layer film on the substrate using the lower layer film forming composition according to any one of claims 8 to 10;
Forming at least one photoresist layer on the lower layer film;
Irradiating a predetermined region of the photoresist layer with radiation and developing,
Resist pattern forming method. Forming a lower layer film on the substrate using the lower layer film forming composition according to any one of claims 8 to 10;
On the lower layer film, a step of forming an intermediate layer film using a resist intermediate layer film material containing silicon atoms,
Forming at least one photoresist layer on the intermediate layer film;
Irradiating a predetermined region of the photoresist layer with radiation to form a developed resist pattern;
Etching the intermediate layer film using the resist pattern as a mask to form an intermediate layer film pattern;
Etching the lower layer film using the intermediate layer film pattern as an etching mask to form a lower layer film pattern;
Using the lower layer film pattern as an etching mask, etching the substrate to form a substrate pattern,
Circuit pattern forming method.